Tag Archives: artificial intelligence

Doubling down on the edge with Coral’s new accelerator

Posted by The Coral Team

Coral image

Moving into the fall, the Coral platform continues to grow with the release of the M.2 Accelerator with Dual Edge TPU. Its first application is in Google’s Series One room kits where it helps to remove interruptions and makes the audio clearer for better video meetings. To help even more folks build products with Coral intelligence, we’re dropping the prices on several of our products. And for those folks that are looking to level up their at home video production, we’re sharing a demo of a pose based AI director to make multi-camera video easier to make.

Coral M.2 Accelerator with Dual Edge TPU

The newest addition to our product family brings two Edge TPU co-processors to systems in an M.2 E-key form factor. While the design requires a dual bus PCIe M.2 slot, it brings enhanced ML performance (8 TOPS) to tasks such as running two models in parallel or pipelining one large model across both Edge TPUs.

The ability to scale across multiple edge accelerators isn’t limited to only two Edge TPUs. As edge computing expands to local data centers, cell towers, and gateways, multi-Edge TPU configurations will be required to help process increasingly sophisticated ML models. Coral allows the use of a single toolchain to create models for one or more Edge TPUs that can address many different future configurations.

A great example of how the Coral M.2 Accelerator with Dual Edge TPU is being used is in the Series One meeting room kits for Google Meet.

The new Series One room kits for Google Meet run smarter with Coral intelligence

Coral image

Google’s new Series One room kits use our Coral M.2 Accelerator with Dual Edge TPU to bring enhanced audio clarity to video meetings. TrueVoice®, a multi-channel noise cancellation technology, minimizes distractions to ensure every voice is heard with up to 44 channels of echo and noise cancellation, making distracting sounds like snacking or typing on a keyboard a concern of the past.

Enabling the clearest possible communication in challenging environments was the target for the Google Meet hardware team. The consideration of what makes a challenging environment was not limited to unusually noisy environments, such as lunchrooms doubling as conference rooms. Any conference room can present challenging acoustics that make it difficult for all participants to be heard.

The secret to clarity without expensive and cumbersome equipment is to use virtual audio channels and AI driven sound isolation. Read more about how Coral was used to enhance and future-proof the innovative design.

Expanding the AI edge

Earlier this year, we reduced the prices of our prototyping devices and sensors. We are excited to share further price drops on more of our products. Our System-on-Module is now available for $99.99, and our Mini PCIe Accelerator, M.2 Accelerator A+E Key, and M.2 Accelerator B+M key are now available at $24.99. We hope this lower price will make our edge AI more accessible to more creative minds around the world. Later, this month our SoM offering will also expand to include 2 and 4GB RAM options.

Multi-cam with AI

Coral image

As we expand our platform and product family, we continue to keep new edge AI use cases in mind. We are continually inspired by our developer community’s experimentation and implementations. When recently faced with the challenges of multicam video production from home, Markku Lepistö, Solutions Architect at Google Cloud, created this real-time pose-based multicam tool he so aptly dubbed, AI Director.

We love seeing such unique implementations of on-device ML and invite you to share your own projects and feedback at [email protected].

For a list of worldwide distributors, system integrators and partners, visit the Coral partnerships page. Please visit Coral.ai to discover more about our edge ML platform.

Doubling down on the edge with Coral’s new accelerator

Posted by The Coral Team

Coral image

Moving into the fall, the Coral platform continues to grow with the release of the M.2 Accelerator with Dual Edge TPU. Its first application is in Google’s Series One room kits where it helps to remove interruptions and makes the audio clearer for better video meetings. To help even more folks build products with Coral intelligence, we’re dropping the prices on several of our products. And for those folks that are looking to level up their at home video production, we’re sharing a demo of a pose based AI director to make multi-camera video easier to make.

Coral M.2 Accelerator with Dual Edge TPU

The newest addition to our product family brings two Edge TPU co-processors to systems in an M.2 E-key form factor. While the design requires a dual bus PCIe M.2 slot, it brings enhanced ML performance (8 TOPS) to tasks such as running two models in parallel or pipelining one large model across both Edge TPUs.

The ability to scale across multiple edge accelerators isn’t limited to only two Edge TPUs. As edge computing expands to local data centers, cell towers, and gateways, multi-Edge TPU configurations will be required to help process increasingly sophisticated ML models. Coral allows the use of a single toolchain to create models for one or more Edge TPUs that can address many different future configurations.

A great example of how the Coral M.2 Accelerator with Dual Edge TPU is being used is in the Series One meeting room kits for Google Meet.

The new Series One room kits for Google Meet run smarter with Coral intelligence

Coral image

Google’s new Series One room kits use our Coral M.2 Accelerator with Dual Edge TPU to bring enhanced audio clarity to video meetings. TrueVoice®, a multi-channel noise cancellation technology, minimizes distractions to ensure every voice is heard with up to 44 channels of echo and noise cancellation, making distracting sounds like snacking or typing on a keyboard a concern of the past.

Enabling the clearest possible communication in challenging environments was the target for the Google Meet hardware team. The consideration of what makes a challenging environment was not limited to unusually noisy environments, such as lunchrooms doubling as conference rooms. Any conference room can present challenging acoustics that make it difficult for all participants to be heard.

The secret to clarity without expensive and cumbersome equipment is to use virtual audio channels and AI driven sound isolation. Read more about how Coral was used to enhance and future-proof the innovative design.

Expanding the AI edge

Earlier this year, we reduced the prices of our prototyping devices and sensors. We are excited to share further price drops on more of our products. Our System-on-Module is now available for $99.99, and our Mini PCIe Accelerator, M.2 Accelerator A+E Key, and M.2 Accelerator B+M key are now available at $24.99. We hope this lower price will make our edge AI more accessible to more creative minds around the world. Later, this month our SoM offering will also expand to include 2 and 4GB RAM options.

Multi-cam with AI

Coral image

As we expand our platform and product family, we continue to keep new edge AI use cases in mind. We are continually inspired by our developer community’s experimentation and implementations. When recently faced with the challenges of multicam video production from home, Markku Lepistö, Solutions Architect at Google Cloud, created this real-time pose-based multicam tool he so aptly dubbed, AI Director.

We love seeing such unique implementations of on-device ML and invite you to share your own projects and feedback at [email protected].

For a list of worldwide distributors, system integrators and partners, visit the Coral partnerships page. Please visit Coral.ai to discover more about our edge ML platform.

Instant Motion Tracking with MediaPipe

Posted by Vikram Sharma, Software Engineering Intern; Jianing Wei, Staff Software Engineer; Tyler Mullen, Senior Software Engineer

Augmented Reality (AR) technology creates fun, engaging, and immersive user experiences. The ability to perform AR tracking across devices and platforms, without initialization, remains important for powering AR applications at scale.

Today, we are excited to release the Instant Motion Tracking solution in MediaPipe. It is built upon the MediaPipe Box Tracking solution we released previously. With Instant Motion Tracking, you can easily place fun virtual 2D and 3D content on static or moving surfaces, allowing them to seamlessly interact with the real world. This technology also powered MotionStills AR. Along with the library, we are releasing an open source Android application to showcase its capabilities. In this application, a user simply taps the camera viewfinder in order to place virtual 3D objects and GIF animations, augmenting the real-world environment.

gif of instant motion tracking in MediaPipe gif of instant motion tracking in MediaPipe

Instant Motion Tracking in MediaPipe

Instant Motion Tracking

The Instant Motion Tracking solution provides the capability to seamlessly place virtual content on static or motion surfaces in the real world. To achieve that, we provide the six degrees of freedom tracking with relative scale in the form of rotation and translation matrices. This tracking information is then used in the rendering system to overlay virtual content on camera streams to create immersive AR experiences.

The core concept behind Instant Motion Tracking is to decouple the camera’s translation and rotation estimation, treating them instead as independent optimization problems. This approach enables AR tracking across devices and platforms without initialization or calibration. We do this by first finding the 3D camera translation using only the visual signals from the camera. This involves estimating the target region's apparent 2D translation and relative scale across frames. The process can be illustrated with a simple pinhole camera model, relating translation and scale of an object in the image plane to the final 3D translation.

image

By finding the change in relative size of our tracked region from view position V1 to V2, we can estimate the relative change in distance from the camera.

Next, we obtain the device’s 3D rotation from its built-in IMU (Inertial Measurement Unit) sensor. By combining this translation and rotation data, we can track a target region with six degrees of freedom at relative scale. This information allows for the placement of virtual content on any system with a camera and IMU functionality, and is calibration free. For more details on Instant Motion Tracking, please refer to our paper.

A MediaPipe Pipeline for Instant Motion Tracking

A diagram of Instant Motion Tracking pipeline is shown below, consisting of four major components: a Sticker Manager module, a Region Tracking module, a Matrices Manager module, and lastly a Rendering System. Each of the components consists of MediaPipe calculators or subgraphs.

Diagram

Diagram of Instant Motion Tracking Pipeline

The Sticker Manager accepts sticker data from the application and produces initial anchors (tracked region information) based on user taps, and user gesture controls for every sticker object. Initial anchors are then sent to our Region Tracking module to generate tracked anchors. The Matrices Manager combines this data with our device’s rotation matrix to produce six degrees-of-freedom poses as model matrices. After integrating any user-specified transforms like asset scaling, our final poses are forwarded to the Rendering System to render all virtual objects overlaid on the camera frame to produce the output AR frame.

Using the Instant Motion Tracking Solution

The Instant Motion Tracking solution is easy to use by leveraging the MediaPipe cross-platform framework. With camera frames, device rotation matrix, and anchor positions (screen coordinates) as input, the MediaPipe graph produces AR renderings for each frame, providing engaging experiences. If you wish to integrate this Instant Motion Tracking library with your system or application, please visit our documentation to build your own AR experiences on any device with IMU functionality and a camera sensor.

Augmenting The World with 3D Stickers and GIFs

Instant Motion Tracking solution allows bringing both 3D stickers and GIF animations into Augmented Reality experiences. GIFs are rendered on flat 3D billboards placed in the world, introducing fun and immersive experiences with animated content blended into the real environment.Try it for yourself!

Demonstration of GIF placement in 3D Demonstration of GIF placement in 3D

Demonstration of GIF placement in 3D

MediaPipe Instant Motion Tracking is already helping PixelShift.AI, a startup applying cutting-edge vision technologies to facilitate video content creation, to track virtual characters seamlessly in the view-finder for a realistic experience. Building upon Instant Motion Tracking’s high-quality pose estimation, PixelShift.AI enables VTubers to create mixed reality experiences with web technologies. The product is going to be released to the broader VTuber community later this year.

Instant

Instant Motion Tracking helps PixelShift.AI create mixed reality experiences

Follow MediaPipe

We look forward to publishing more blog posts related to new MediaPipe pipeline examples and features. Please follow the MediaPipe label on Google Developers Blog and Google Developers twitter account (@googledevs).

Acknowledgement

We would like to thank Vikram Sharma, Jianing Wei, Tyler Mullen, Chuo-Ling Chang, Ming Guang Yong, Jiuqiang Tang, Siarhei Kazakou, Genzhi Ye, Camillo Lugaresi, Buck Bourdon, and Matthias Grundman for their contributions to this release.

Summer updates from Coral

Posted by the Coral Team

Summer has arrived along with a number of Coral updates. We're happy to announce a new partnership with balena that helps customers build, manage, and deploy IoT applications at scale on Coral devices. In addition, we've released a series of updates to expand platform compatibility, make development easier, and improve the ML capabilities of our devices.

Open-source Edge TPU runtime now available on GitHub

First up, our Edge TPU runtime is now open-source and available on GitHub, including scripts and instructions for building the library for Linux and Windows. Customers running a platform that is not officially supported by Coral, including ARMv7 and RISC-V can now compile the Edge TPU runtime themselves and start experimenting. An open source runtime is easier to integrate into your customized build pipeline, enabling support for creating Yocto-based images as well as other distributions.

Windows drivers now available for the Mini PCIe and M.2 accelerators

Coral customers can now also use the Mini PCIe and M.2 accelerators on the Microsoft Windows platform. New Windows drivers for these products complement the previously released Windows drivers for the USB accelerator and make it possible to start prototyping with the Coral USB Accelerator on Windows and then to move into production with our Mini PCIe and M.2 products.

New fresh bits on the Coral ML software stack

We’ve also made a number of new updates to our ML tools:

  • The Edge TPU compiler is now version 14.1. It can be updated by running sudo apt-get update && sudo apt-get install edgetpu, or follow the instructions here
  • Our new Model Pipelining API allows you to divide your model across multiple Edge TPUs. The C++ version is currently in beta and the source is on GitHub
  • New embedding extractor models for EfficientNet, for use with on-device backpropagation. Embedding extractor models are compiled with the last fully-connected layer removed, allowing you to retrain for classification. Previously, only Inception and MobileNet were available and now retraining can also be done on EfficientNet
  • New Colab notebooks to retrain a classification model with TensorFlow 2.0 and build C++ examples

Balena partners with Coral to enable AI at the edge

We are excited to share that the Balena fleet management platform now supports Coral products!

Companies running a fleet of ML-enabled devices on the edge need to keep their systems up-to-date with the latest security patches in order to protect data, model IP and hardware from being compromised. Additionally, ML applications benefit from being consistently retrained to recognize new use cases with maximum accuracy. Coral + balena together, bring simplicity and ease to the provisioning, deployment, updating, and monitoring of your ML project at the edge, moving early prototyping seamlessly towards production environments with many thousands of devices.

Read more about all the benefits of Coral devices combined with balena container technology or get started deploying container images to your Coral fleet with this demo project.

New version of Mendel Linux

Mendel Linux (5.0 release Eagle) is now available for the Coral Dev Board and SoM and includes a more stable package repository that provides a smoother updating experience. It also brings compatibility improvements and a new version of the GPU driver.

New models

Last but not least, we’ve recently released BodyPix, a Google person-segmentation model that was previously only available for TensorFlow.JS, as a Coral model. This enables real-time privacy preserving understanding of where people (and body parts) are on a camera frame. We first demoed this at CES 2020 and it was one of our most popular demos. Using BodyPix we can remove people from the frame, display only their outline, and aggregate over time to see heat maps of population flow.

Here are two possible applications of BodyPix: Body-part segmentation and anonymous population flow. Both are running on the Dev Board.

We’re excited to add BodyPix to the portfolio of projects the community is using to extend our models far beyond our demos—including tackling today’s biggest challenges. For example, Neuralet has taken our MobileNet V2 SSD Detection model and used it to implement Smart Social Distancing. Using the bounding box of person detection, they can compute a region for safe distancing and let a user know if social distance isn’t being maintained. The best part is this is done without any sort of facial recognition or tracking, with Coral we can accomplish this in real-time in a privacy preserving manner.

We can’t wait to see more projects that the community can make with BodyPix. Beyond anonymous population flow there’s endless possibilities with background and body part manipulation. Let us know what you come up with at our community channels, including GitHub and StackOverflow.

________________________

We are excited to share all that Coral has to offer as we continue to evolve our platform. For a list of worldwide distributors, system integrators and partners, including balena, visit the Coral partnerships page. Please visit Coral.ai to discover more about our edge ML platform and share your feedback at [email protected].

13 Most Common Google Cloud Reference Architectures

Posted by Priyanka Vergadia, Developer Advocate

Google Cloud is a cloud computing platform that can be used to build and deploy applications. It allows you to take advantage of the flexibility of development while scaling the infrastructure as needed.

I'm often asked by developers to provide a list of Google Cloud architectures that help to get started on the cloud journey. Last month, I decided to start a mini-series on Twitter called “#13DaysOfGCP" where I shared the most common use cases on Google Cloud. I have compiled the list of all 13 architectures in this post. Some of the topics covered are hybrid cloud, mobile app backends, microservices, serverless, CICD and more. If you were not able to catch it, or if you missed a few days, here we bring to you the summary!

Series kickoff #13DaysOfGCP

#1: How to set up hybrid architecture in Google Cloud and on-premises

Day 1

#2: How to mask sensitive data in chatbots using Data loss prevention (DLP) API?

Day 2

#3: How to build mobile app backends on Google Cloud?

Day 3

#4: How to migrate Oracle Database to Spanner?

Day 4

#5: How to set up hybrid architecture for cloud bursting?

Day 5

#6: How to build a data lake in Google Cloud?

Day 6

#7: How to host websites on Google Cloud?

Day 7

#8: How to set up Continuous Integration and Continuous Delivery (CICD) pipeline on Google Cloud?

Day 8

#9: How to build serverless microservices in Google Cloud?

Day 9

#10: Machine Learning on Google Cloud

Day 10

#11: Serverless image, video or text processing in Google Cloud

Day 11

#12: Internet of Things (IoT) on Google Cloud

Day 12

#13: How to set up BeyondCorp zero trust security model?

Day 13

Wrap up with a puzzle

Wrap up!

We hope you enjoy this list of the most common reference architectures. Please let us know your thoughts in the comments below!

Building a more resilient world together

Posted by Billy Rutledge, Director of the Coral team

UNDP Hackster.io COVID19 Detect Protect Poster

Recently, we’ve seen communities respond to the challenges of the coronavirus pandemic by using technology in new ways to effect positive change. It’s increasingly important that our systems are able to adapt to new contexts, handle disruptions, and remain efficient.

At Coral, we believe intelligence at the edge is a key ingredient towards building a more resilient future. By making the latest machine learning tools easy-to-use and accessible, innovators can collaborate to create solutions that are most needed in their communities. Developers are already using Coral to build solutions that can understand and react in real-time, while maintaining privacy for everyone present.

Helping our communities stay safe, together

As mandatory isolation measures begin to relax, compliance with safe social distancing protocol has become a topic of primary concern for experts across the globe. Businesses and individuals have been stepping up to find ways to use technology to help reduce the risk and spread. Many efforts are employing the benefits of edge AI—here are a few early stage examples that have inspired us.

woman and child crossing the street

In Belgium, engineers at Edgise recently used Coral to develop an occupancy monitor to aid businesses in managing capacity. With the privacy preserving properties of edge AI, businesses can anonymously count how many customers enter and exit a space, signaling when the area is too full.

A research group at the Sathyabama Institute of Science and Technology in India are using Coral to develop a wearable device to serve as a COVID-19 cough counter and health monitor, allowing medical professionals to better care for low risk patients in an outpatient capacity. Coral's Edge TPU enables biometric data to be processed efficiently, without draining the limited power resources available in wearable devices.

All across the US, hospitals are seeking solutions to ensure adherence to hygiene policy amongst hospital staff. In one example, a device incorporates the compact, affordable and offline benefits of the Coral modules to aid in handwashing practices at numerous stations throughout a facility.

And around the world, members of the PyImageSearch community are exploring how to train a COVID-19: Face Mask Detector model using TensorFlow that can be used to identify whether people are wearing a mask. Open source frameworks can empower anyone to develop solutions, and with Coral components we can help bring those benefits to everyone.

Eliciting a global response

In an effort to rally greater community involvement, Coral has joined The United Nations Development Programme and Hackster.io, as a sponsor of the COVID-19 Detect and Protect Challenge. The initiative calls on developers to build affordable and reproducible solutions that support response efforts in developing countries. All ideas are welcome—whether they use ML or not—and we encourage you to participate.

To make edge ML capabilities even easier to integrate, we’re also announcing a price reduction for the Coral products widely used for experimentation and prototyping. Our Dev Board will now be offered at $129.99, the USB Accelerator at $59.99, the Camera Module at $19.99, and the Enviro Board at $14.99. Additionally, we are introducing the USB Accelerator into 10 new markets: Ghana, Thailand, Singapore, Oman, Philippines, Indonesia, Kenya, Malaysia, Israel, and Vietnam. For more details, visit Coral.ai/products.

We’re excited to see the solutions developers will bring forward with Coral. And as always, please keep sending us feedback at [email protected]

MediaPipe KNIFT: Template-based Feature Matching

Posted by Zhicheng Wang and Genzhi Ye, MediaPipe team

Image Feature Correspondence with KNIFT

In many computer vision applications, a crucial building block is to establish reliable correspondences between different views of an object or scene, forming the foundation for approaches like template matching, image retrieval and structure from motion. Correspondences are usually computed by extracting distinctive view-invariant features such as SIFT or ORB from images. The ability to reliably establish such correspondences enables applications like image stitching to create panoramas or template matching for object recognition in videos (see Figure 1).

Today, we are announcing KNIFT (Keypoint Neural Invariant Feature Transform), a general purpose local feature descriptor similar to SIFT or ORB. Likewise, KNIFT is also a compact vector representation of local image patches that is invariant to uniform scaling, orientation, and illumination changes. However unlike SIFT or ORB, which were engineered with heuristics, KNIFT is an embedding learned directly from a large number of corresponding local patches extracted from nearby video frames. This data driven approach implicitly encodes complex, real-world spatial transformations and lighting changes in the embedding. As a result, the KNIFT feature descriptor appears to be more robust, not only to affine distortions, but to some degree of perspective distortions as well. We are releasing an implementation of KNIFT in MediaPipe and a KNIFT-based template matching demo in the next section to get you started.

Figure 1: Matching a real Stop Sign with a Stop Sign template using KNIFT.

Training Method

In Machine Learning, loosely speaking, training an embedding means finding a mapping that can translate a high dimensional vector, such as an image patch, to a relatively lower dimensional vector, such as a feature descriptor. Ideally, this mapping should have the following property: image patches around a real-world point should have the same or very similar descriptors across different views or illumination changes. We have found real world videos a good source of such corresponding image patches as training data (See Figure 3 and 4) and we use the well-established Triplet Loss (see Figure 2) to train such an embedding. Each triplet consists of an anchor (denoted by a), a positive (p), and a negative (n) feature vector extracted from the corresponding image patches, and d() denotes the Euclidean distance in the feature space.

Figure 2: Triplet Loss Function.

Figure 2: Triplet Loss Function.

Training Data

The training triplets are extracted from all ~1500 video clips in the publicly available YouTube UGC Dataset. We first use an existing heuristically-engineered local feature detector to detect keypoints and compute the affine transform between two frames with a high accuracy (see Figure 4). Then we use this correspondence to find keypoint pairs and extract the patches around these keypoints. Note that the newly identified keypoints may include those that were detected but rejected by geometric verification in the first step. For each pair of matched patches, we randomly apply some form of data augmentation (e.g. random rotation or brightness adjustment) to construct the anchor-positive pair. Finally, we randomly pick an arbitrary patch from another video as the negative to finish the construction of this triplet (see Figure 5).

Figure 3: An example video clip from which we extract training triplets.

Figure 4: Finding frame correspondence using existing local features.

Figure 5: (Top to bottom) Anchor, positive and negative patches.

Hard-negative Triplet Mining

To improve model quality, we use the same hard-negative triplet mining method used by FaceNet training. We first train a base model with randomly selected triplets. Then we implement a pipeline that uses the base model to find semi-hard-negative samples (d(a,p) < d(a,n) < d(a,p)+margin) for each anchor-positive pair (Figure 6). After mixing the randomly selected triplets and hard-negative triplets, we re-train the model with this improved data.

Figure 6: (Top to bottom) Anchor, positive and semi-hard negative patches.

Model Architecture

From model architecture exploration, we have found that a relatively small architecture is sufficient to achieve decent quality, so we use a lightweight version of the Inception architecture as the KNIFT model backbone. The resulting KNIFT descriptor is a 40-dimensional float vector. For more model details, please refer to the KNIFT model card.

Benchmark

We benchmark the KNIFT model inference speed on various devices (computing 200 features) and list them in Table 1.

Table 1: KNIFT performance benchmark.

Table 1: KNIFT performance benchmark.

Quality-wise, we compare the average number of keypoints matched by KNIFT and by ORB (OpenCV implementation) respectively on an in-house benchmark (Table 2). There are many publicly available image matching benchmarks, e.g. 2020 Image Matching Benchmark, but most of them focus on matching landmarks across large perspective changes in relatively high resolution images, and the tasks often require computing thousands of keypoints. In contrast, since we designed KNIFT for matching objects in large scale (i.e. billions of images) online image retrieval tasks, we devised our benchmark to focus on low cost and high precision driven use cases, i.e. 100-200 keypoints computed per image and only ~10 matching keypoints needed for reliably determining a match. In addition, to illustrate the fine-grained performance characteristics of a feature descriptor, we divide and categorize the benchmark set by object types (e.g. 2D planar surface) and image pair relations (e.g. large size difference). In table 2, we compare the average number of keypoints matched by KNIFT and by ORB respectively in each category, based on the same 200 keypoint locations detected in each image by the oFast detector that comes with the ORB implementation in OpenCV.

Table 2: KNIFT vs ORB average number of matched keypoints.

From Table 2, we can see that KNIFT consistently matches more keypoints than ORB by a large margin in every category. Here we acknowledge the fact that KNIFT (40-d float) is considerably larger than ORB (32-d char) and this can have an effort on matching quality. Nevertheless, most local feature benchmarks do not take descriptor size into account so we will follow the convention here.

To make it easy for developers to try KNIFT in MediaPIpe, we have built a local-feature-based template matching solution (see implementation details using MediaPipe in the next section). As a side effect, we can demonstrate the matching quality between KNIFT and ORB visually in side-by-side comparisons like Figure 7 and 9.

Figure 7: Example of “matching 2D planar surface”. (Left) KNIFT 183/240, (Right) ORB 133/240.

In Figure 7, we choose a typical U.S. Stop Sign image from Google Image Search as the template and attempt to match it with the Stop Sign in this video. This example falls into the “matching 2D planar surface” category in Table 2. Using the same 200 keypoint locations detected by oFast and the same RANSAC setting, we show that KNIFT is successful at matching the Stop Sign in 183 frames out of a total of 240 frames. In comparison, ORB matches 133 frames.

Figure 8: Example of “matching 3D untextured object”. Two template images from different views.

Figure 9: Example of “matching 3D untextured object”. (Left) KNIFT 89/150, (Right) ORB 37/150.

Figure 9 shows another matching performance comparison on an example from the “matching 3D untextured object” category in Table 2. Since this example involves large perspective changes of untextured surfaces, which is known to be challenging for local feature descriptors, we use template images from two different views (shown in Figure 8) to improve the matching performance. Again, using the same keypoint locations and RANSAC setting, we show that KNIFT is successful at matching 89 frames out of a total of 150 frames while ORB matches 37 frames.

KNIFT-based Template Matching in MediaPipe

We are releasing the aforementioned template matching solution based on KNIFT in MediaPipe, which is capable of identifying pre-defined image templates and precisely localizing recognized templates on the camera image. There are 3 major components in the template-matching MediaPipe graph shown below:

  • FeatureDetectorCalculator: a calculator that consumes image frames and performs OpenCV oFast detector on the input image and outputs keypoint locations. Moreover, this calculator is also responsible for cropping patches around each keypoint with rotation and scale info and stacking them into a vector for the downstream calculator to process.
  • TfLiteInferenceCalculator with KNIFT model: a calculator that loads the KNIFT tflite model and performs model inference. The input tensor shape is (200, 32, 32, 1), indicating 200 32x32 local patches. The output tensor shape is (200, 40), indicating 200 40-dimensional feature descriptors. By default, the calculator runs the TFLite XNNPACK delegate, but users have the option to select the regular CPU delegate to run at a reduced speed.
  • BoxDetectorCalculator: a calculator that takes pre-computed keypoint locations and KNIFT descriptors and performs feature matching between the current frame and multiple template images. The output of this calculator is a list of TimedBoxProto, which contains the unique id and location of each box as a quadrilateral on the image. Aside from the classic homography RANSAC algorithm, we also apply a perspective transform verification step to ensure that the output quadrilateral does not result in too much skew or a weird shape.

Figure 10: MediaPipe graph of the demo

Demo

In this demo, we chose three different denominations ($1, $5, $20) of U.S. dollar bills as templates and attempted to match them to various real world dollar bills in videos. We resized each input frame to 640x480 pixels, ran the oFast detector to detect 200 keypoints, and used KNIFT to extract feature descriptors from each 32x32 local image patch surrounding these keypoints. We then performed template matching between these video frames and the KNIFT features extracted from the dollar bill templates. This demo runs at 20 FPS on a Pixel 2 Phone CPU with XNNPACK.

Figure 11: Matching different U.S. dollar bills using KNIFT.

Build Your Own Templates

We have provided a set of built-in planar templates in our demo. To make it easy for users to try their own templates, we also provide a tool to build such an index with user generated templates. index_building.pbtxt is a MediaPipe graph that accepts as its input a directory path containing a set of template images. Users can use this graph to compute KNIFT descriptors for all template images (which will be stored in a single file) by 1) replacing the index_proto_filename field in the main graph and the BUILD file and 2) rebuilding the APK file. For step-by-step instructions on how we created the dollar bill demo shown above, please refer to this documentation.

Acknowledgements

We would like to thank Jiuqiang Tang, Chuo-Ling Chang, Dan Gnanapragasam‎, Howard Zhou, Jianing Wei and Ming Guang Yong for contributing to this blog post.

Alfred Camera: Smart camera features using MediaPipe

Guest post by the Engineering team at Alfred Camera

Please note that the information, uses, and applications expressed in the below post are solely those of our guest author, Alfred Camera.

In this article, we’d like to give you a short overview of Alfred Camera and our experience of using MediaPipe to transform our moving object feature, and how MediaPipe has helped to get things easier to achieve our goals.

What is Alfred Camera?

AlfredCamera logo

Fig.1 Alfred Camera Logo

Alfred Camera is a smart home app for both Android and iOS devices, with over 15 million downloads worldwide. By downloading the app, users are able to turn their spare phones into security cameras and monitors directly, which allows them to watch their homes, shops, pets anytime. The mission of Alfred Camera is to provide affordable home security so that everyone can find peace of mind in this busy world.

The Alfred Camera team is composed of professionals in various fields, including an engineering team with several machine learning and computer vision experts. Our aim is to integrate AI technology into devices that are accessible to everyone.

Machine Learning in Alfred Camera

Alfred Camera currently has a feature called Moving Object Detection, which continuously uses the device’s camera to monitor a target scene. Once it identifies a moving object in the area, the app will begin recording the video and send notifications to the device owner. The machine learning models for detection are hand-crafted and trained by our team using TensorFlow, and run on TensorFlow Lite with good performance even on mid-tier devices. This is important because the app is leveraging old phones and we'd like the feature to reach as many users as possible.

The Challenges

We had started building our AI features at Alfred Camera since 2017. In order to have a solid foundation to support our AI feature requirements for the coming years, we decided to rebuild our real-time video analysis pipeline. At the beginning of the project, the goals were to create a new pipeline which should be 1) modular enough so we could swap core algorithms easily with minimal changes in other parts of the pipeline, 2) having GPU acceleration designed in place, 3) cross-platform as much as possible so there’s no need to create/maintain separate implementations for different platforms. Based on the goals, we had surveyed several open source projects that had the potential but we ended up using none of them as they either fell short on the features or were not providing the readiness/stabilities that we were looking for.

We started a small team to prototype on those goals first for the Android platform. What came later were some tough challenges way above what we originally anticipated. We ran into several major design changes as some key design basics were overlooked. We needed to implement some utilities to do things that sounded trivial but required significant effort to make it right and fast. Dealing with asynchronous processing also led us into a bunch of timing issues, which took the team quite some effort to address. Not to mention debugging on real devices was extremely inefficient and painful.

Things didn't just stop here. Our product is also on iOS and we had to tackle these challenges once again. Moreover, discrepancies in the behavior between the platform-specific implementations introduced additional issues that we needed to resolve.

Even though we finally managed to get the implementations to the confidence level we wanted, that was not a very pleasant experience and we have never stopped thinking if there is a better option.

MediaPipe - A Game Changer

Google open sourced MediaPipe project in June 2019 and it immediately caught our attention. We were surprised by how it is perfectly aligned with the previous goals we set, and has functionalities that could not have been developed with the amount of engineering resources we had as a small company.

We immediately decided to start an evaluation project by building a new product feature directly using MediaPipe to see if it could live up to all the promises.

Migrating to MediaPipe

To start the evaluation, we decided to migrate our existing moving object feature to see what exactly MediaPipe can do.

Our current Moving Object Detection pipeline consists of the following main components:

  • (Moving) Object Detection Model
    As explained earlier, a TensorFlow Lite model trained by our team, tailored to run on mid-tier devices.
  • Low-light Detection and Low-light Filter
    Calculate the average luminance of the scene, and based on the result conditionally process the incoming frames to intensify the brightness of the pixels to let our users see things in the dark. We are also controlling whether we should run the detection or not as the moving object detection model does not work properly when the frame has been processed by the filter.
  • Motion Detection
    Sending frames through Moving Object Detection still consumes a significant amount of power even with a small model like the one we created. Running inferences continuously does not seem to be a good idea as most of the time there may not be any moving object in front of the camera. We decided to implement a gating mechanism where the frames are only being sent to the Moving Object Detection model based on the movements detected from the scene. The detection is done mainly by calculating the differences between two frames with some additional tricks that take the movements detected in a few frames before into consideration.
  • Area of Interest
    This is a mechanism to let users manually mask out the area where they do not want the camera to see. It can also be done automatically based on regional luminance that can be generated by the aforementioned low-light detection component.

Our current implementation has taken GPU into consideration as much as we can. A series of shaders are created to perform the tasks above and the pipeline is designed to avoid moving pixels between CPU/GPU frequently to eliminate the potential performance hits.

The pipeline involves multiple ML models that are conditionally executed, mixed CPU/GPU processing, etc. All the challenges here make it a perfect showcase for how MediaPipe could help develop a complicated pipeline.

Playing with MediaPipe

MediaPipe provides a lot of code samples for any developer to bootstrap with. We took the Object Detection on Android sample that comes with the project to start with because of the similarity with the back-end part of our pipeline. It did take us sometimes to fully understand the design concepts of MediaPipe and all the tools associated. But with the complete documentation and the great responsiveness from the MediaPipe team, we got up to speed soon to do most of the things we wanted.

That being said, there were a few challenges we needed to overcome on the road to full migration. Our original pipeline of Moving Object Detection takes the input frame asynchronously, but MediaPipe has timestamp bound limitations such that we cannot just show the result in an allochronic way. Meanwhile, we need to gather data through JNI in a specific data format. We came up with a workaround that conquered all the issues under the circumstances, which will be mentioned later.

After wrapping our models and the processing logics into calculators and wired them up, we have successfully transformed our existing implementation and created our first MediaPipe Moving Object Detection pipeline like the figure below, running on Android devices:

Fig.2 Moving Object Detection Graph

Fig.2 Moving Object Detection Graph

We do not block the video frame in the main calculation loop, and set the detection result as an input stream to show the annotation on the screen. The whole graph is designed as a multi-functioned process, the left chunk is the debug annotation and video frame output module, and the rest of the calculation occurs in the rest of the graph, e.g., low light detection, motion triggered detection, cropping of the area of interest and the detection process. In this way, the graph process will naturally separate into real-time display and asynchronous calculation.

As a result, we are able to complete a full processing for detection in under 40ms on a device with Snapdragon 660 chipset. MediaPipe’s tight integration with TensorFlow Lite provides us the flexibility to get even more performance gain by leveraging whatever acceleration techniques available (GPU or DSP) on the device.

The following figure shows the current implementation working in action:

Fig.3 Moving Object Detection running in Alfred Camera

Fig.3 Moving Object Detection running in Alfred Camera

After getting things to run on Android, Desktop GPU (OpenGL-ES) emulation was our next target to evaluate. We are already using OpenGL-ES shaders for some computer vision operations in our pipeline. Having the capability to develop the algorithm on desktop, seeing it work in action before deployment onto mobile platforms is a huge benefit to us. The feature was not ready at the time when the project was first released, but MediaPipe team had soon added Desktop GPU emulation support for Linux in follow-up releases to make this possible. We have used the capability to detect and fix some issues in the graphs we created even before we put things on the mobile devices. Although it currently only works on Linux, it is still a big leap forward for us.

Testing the algorithms and making sure they behave as expected is also a challenge for a camera application. MediaPipe helps us simplify this by using pre-recorded MP4 files as input so we could verify the behavior simply by replaying the files. There is also built-in profiling support that makes it easy for us to locate potential performance bottlenecks.

MediaPipe - Exactly What We Were Looking For

The result of the evaluation and the feedback from our engineering team were very positive and promising:

  1. We are able to design/verify the algorithm and complete core implementations directly on the desktop emulation environment, and then migrate to the target platforms with minimum efforts. As a result, complexities of debugging on real devices are greatly reduced.
  2. MediaPipe’s modular design of graphs/calculators enables us to better split up the development into different engineers/teams, try out new pipeline design easily by rewiring the graph, and test the building blocks independently to ensure quality before we put things together.
  3. MediaPipe’s cross-platform design maximizes the reusability and minimizes fragmentation of the implementations we created. Not only are the efforts required to support a new platform greatly reduced, but we are also less worried about the behavior discrepancies on different platforms due to different interpretations of the spec from platform engineers.
  4. Built-in graphics utilities and profiling support saved us a lot of time creating those common facilities and making them right, and we could be more focused on the key designs.
  5. Tight integration with TensorFlow Lite really saves lots of effort for a company like us that heavily depends on TensorFlow, and it still gives us the flexibility to easily interface with other solutions.

With just a few weeks working with MediaPipe, it has shown strong capabilities to fundamentally transform how we develop our products. Without MediaPipe we could have spent months creating the same features without the same level of performance.

Summary

Alfred Camera is designed to bring home security with AI to everyone, and MediaPipe has significantly made achieving that goal easier for our team. From Moving Object Detection to future AI-powered features, we are focusing on transforming a basic security camera use case into a smart housekeeper that can help provide even more context that our users care about. With the support of MediaPipe, we have been able to accelerate our development process and bring the features to the market at an unprecedented speed. Our team is really excited about how MediaPipe could help us progress and discover new possibilities, and is looking forward to the enhancements that are yet to come to the project.

MediaPipe on the Web

Posted by Michael Hays and Tyler Mullen from the MediaPipe team

MediaPipe is a framework for building cross-platform multimodal applied ML pipelines. We have previously demonstrated building and running ML pipelines as MediaPipe graphs on mobile (Android, iOS) and on edge devices like Google Coral. In this article, we are excited to present MediaPipe graphs running live in the web browser, enabled by WebAssembly and accelerated by XNNPack ML Inference Library. By integrating this preview functionality into our web-based Visualizer tool, we provide a playground for quickly iterating over a graph design. Since everything runs directly in the browser, video never leaves the user’s computer and each iteration can be immediately tested on a live webcam stream (and soon, arbitrary video).

Running the MediaPipe face detection example in the Visualizer

Figure 1 shows the running of the MediaPipe face detection example in the Visualizer

MediaPipe Visualizer

MediaPipe Visualizer (see Figure 2) is hosted at viz.mediapipe.dev. MediaPipe graphs can be inspected by pasting graph code into the Editor tab or by uploading that graph file into the Visualizer. A user can pan and zoom into the graphical representation of the graph using the mouse and scroll wheel. The graph will also react to changes made within the editor in real time.

MediaPipe Visualizer hosted at https://viz.mediapipe.dev

Figure 2 MediaPipe Visualizer hosted at https://viz.mediapipe.dev

Demos on MediaPipe Visualizer

We have created several sample Visualizer demos from existing MediaPipe graph examples. These can be seen within the Visualizer by visiting the following addresses in your Chrome browser:

Edge Detection

Face Detection

Hair Segmentation

Hand Tracking

Edge detection
Face detection
Hair segmentation
Hand tracking

Each of these demos can be executed within the browser by clicking on the little running man icon at the top of the editor (it will be greyed out if a non-demo workspace is loaded):

This will open a new tab which will run the current graph (this requires a web-cam).

Implementation Details

In order to maximize portability, we use Emscripten to directly compile all of the necessary C++ code into WebAssembly, which is a special form of low-level assembly code designed specifically for web browsers. At runtime, the web browser creates a virtual machine in which it can execute these instructions very quickly, much faster than traditional JavaScript code.

We also created a simple API for all necessary communications back and forth between JavaScript and C++, to allow us to change and interact with the MediaPipe graph directly from JavaScript. For readers familiar with Android development, you can think of this as a similar process to authoring a C++/Java bridge using the Android NDK.

Finally, we packaged up all the requisite demo assets (ML models and auxiliary text/data files) as individual binary data packages, to be loaded at runtime. And for graphics and rendering, we allow MediaPipe to automatically tap directly into WebGL so that most OpenGL-based calculators can “just work” on the web.

Performance

While executing WebAssembly is generally much faster than pure JavaScript, it is also usually much slower than native C++, so we made several optimizations in order to provide a better user experience. We utilize the GPU for image operations when possible, and opt for using the lightest-weight possible versions of all our ML models (giving up some quality for speed). However, since compute shaders are not widely available for web, we cannot easily make use of TensorFlow Lite GPU machine learning inference, and the resulting CPU inference often ends up being a significant performance bottleneck. So to help alleviate this, we automatically augment our “TfLiteInferenceCalculator” by having it use the XNNPack ML Inference Library, which gives us a 2-3x speedup in most of our applications.

Currently, support for web-based MediaPipe has some important limitations:

  • Only calculators in the demo graphs above may be used
  • The user must edit one of the template graphs; they cannot provide their own from scratch
  • The user cannot add or alter assets
  • The executor for the graph must be single-threaded (i.e. ApplicationThreadExecutor)
  • TensorFlow Lite inference on GPU is not supported

We plan to continue to build upon this new platform to provide developers with much more control, removing many if not all of these limitations (e.g. by allowing for dynamic management of assets). Please follow the MediaPipe tag on the Google Developer blog and Google Developer twitter account. (@googledevs)

Acknowledgements

We would like to thank Marat Dukhan, Chuo-Ling Chang, Jianing Wei, Ming Guang Yong, and Matthias Grundmann for contributing to this blog post.

New Coral products for 2020

Posted by Billy Rutledge, Director Google Research, Coral Team

More and more industries are beginning to recognize the value of local AI, where the speed of local inference allows considerable savings on bandwidth and cloud compute costs, and keeping data local preserves user privacy.

Last year, we launched Coral, our platform of hardware components and software tools that make it easy to prototype and scale local AI products. Our product portfolio includes the Coral Dev Board, USB Accelerator, and PCIe Accelerators, all now available in 36 countries.

Since our release, we’ve been excited by the diverse range of applications already built on Coral across a broad set of industries that range from healthcare to agriculture to smart cities. And for 2020, we’re excited to announce new additions to the Coral platform that will expand the possibilities even further.

First up is the Coral Accelerator Module, an easy to integrate multi-chip package that encapsulates the Edge TPU ASIC. The module exposes both PCIe and USB interfaces and can easily integrate into custom PCB designs. We’ve been working closely with Murata to produce the module and you can see a demo at CES 2020 by visiting their booth at the Las Vegas Convention Center, Tech East, Central Plaza, CP-18. The Coral Accelerator Module will be available in the first half of 2020.

Coral Accelerator Module, a new multi-chip module with Google Edge TPU

Coral Accelerator Module, a new multi-chip module with Google Edge TPU

Next, we’re announcing the Coral Dev Board Mini, which provides a smaller form-factor, lower-power, and lower-cost alternative to the Coral Dev Board. The Mini combines the new Coral Accelerator Module with the MediaTek 8167s SoC to create a board that excels at 720P video encoding/decoding and computer vision use cases. The board will be on display during CES 2020 at the MediaTek showcase located in the Venetian, Tech West, Level 3. The Coral Dev Board Mini will be available in the first half of 2020.

We're also offering new variations to the Coral System-on-Module, now available with 2GB and 4GB LPDDR4 RAM in addition to the original 1GB LPDDR4 configuration. We’ll be showcasing how the SoM can be used in smart city, manufacturing, and healthcare applications, as well as a few new SoC and MCU explorations we’ve been working on with the NXP team at CES 2020 in their pavilion located at the Las Vegas Convention Center, Tech East, Central Plaza, CP-18.

Finally, Asus has chosen the Coral SOM as the base to their Tinker Edge T product, a maker friendly single-board computer that features a rich set of I/O interfaces, multiple camera connectors, programmable LEDs, and color-coded GPIO header. The Tinker Edge T board will be available soon -- more details can be found here from Asus.

Come visit Coral at CES Jan 7-10 in Las Vegas:

  • NXP exhibit (LVCC, Tech East, Central Plaza, CP-18)
  • Mediatek exhibit (Venetian, Tech West, Level 3)
  • Murata exhibit (LVCC, South Hall 2, MP26061)

And, as always, we are always looking for ways to improve the platform, so keep reaching out to us at [email protected]