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  Frequently asked Questions (FAQ)

 
1. Tara - FAQ
 
  1.1 What is the range of the Depth measured by the camera?
  1.2 Is the Tara camera pre-calibrated?
  1.3 Where is the calibrated data of the camera stored?
  1.4 What is IMU? How do we configure it?
  1.5 What is the calibrated file's format?
  1.6 What are the output formats supported in the Tara Camera?
2. Tara SDK
 
  2.1 What is Tara SDK?
  2.2 How to install the SDK?
  2.3 What are the applications provided in the Tara SDK Package?
  2.4 What are the platforms and OS supported by the SDK?
  2.5 Does the SDK come with the source code?
  2.6 What is the Disparity algorithm used in the SDK?
  2.7 What are the output formats supported by SDK?
  2.8 What is the procedure to be followed while building OpenCV?
  2.9 Is it mandatory to have OpenCV to test the SDK samples?
  2.10 Do the SDK applications use rectified images?
  2.11 In the SDK, can the Exposure and Brightness of the camera altered in run time?
  2.12 Where are the documents mentioned in the FAQ found?
  2.13 How to resolve the error "Failed Reading Intrinsic and Extrinsic Files" while executing the sample applications in the Tara SDK?
  2.14 How to overwrite the calibration data pre loaded in the camera flash?
3. Reference design - HW
 
  3.1 What does e-con Systems' reference design provide for developers and OEMs?
  3.2 How do we know that the cameras are perfectly in Sync? Is there any metrics to detect how closely the Sync is?
  3.3 What is the camera sensor that is used in the Tara reference design?
  3.4 Can the camera support color?
  3.5 What is the shutter type on the sensor?
  3.6 What is the lens mount used?
  3.7 Can I change the lens mount from S mount to C mount?
  3.8 Where can I get the datasheet of the lens?
  3.9 Can I have a different sensor integrated other than the MT9V024? The MT9V024 is a
  small resolution sensor and I would like to integrate OV5642 since it as 5MP. Along with the depth, I also want to shoot a picture
  3.10 I would like to buy my own lens instead of the lens provided by e-con Systems. Is this possible?
  3.11 What is the pricing of this reference design?
  3.12 I would like a camera board with a different base line. Can e-con do that?
  3.13 I would like to buy Tara with a different lens. Whom should I contact?
4. Reference Design - SW
 
  4.1 What are the sample applications provided along with this reference design kit?
  4.2 I understand that e-con Systems' provides sample depth measurement applications along with the kit. What is the number of bits/pixel information that is provided?
  4.3 Can I get the source code of this application?
  4.4 Can the working distance be varied? If yes, how?
  4.5 I want to have the depth measurement from 1-10 meters. Can it be done?
  4.6 What is Calibration? Why should I do that?
  4.7 Is there any way that I can just use the reference design directly without making any Calibration? I find it too long a process.
  4.8 I would like the lens to be fitted in and sent to me so that everything is recalibrated and I don't need to do calibration when I get them. Is this possible?
  4.9 Can I get the depth of each and every pixel in the depth measurement application?
  4.10 What is the maximum resolution that can be captured? What is the frame rate at this resolution?
   
 1. Tara - FAQ
  
1.1 What is the range of the Depth measured by the camera?
 
Depth Range is from 50 cm to 300cm. The maximum working distance varies with the lens. With our default lens, the maximum working distance is about 300cm, beyond which the depth accuracy drops down
 
1.2 Is the Tara camera pre-calibrated?
 
Yes, the camera is factory calibrated. Do not disturb the casing or the lens, which would alter the calibration done.
 
1.3 Where is the calibrated data of the camera stored?
 
The calibrated data is stored in the flash memory of the camera. The SDK applications get access to it through the extension unit API's.
1.4 What is IMU? How do we configure it?
 
Inertial Measurement Units (IMUs) is a self-contained system that measures linear and angular motion usually with a triad of gyroscopes and triad of accelerometers and sometimes the magnetic field surrounding the body, also magnetometers.

Tara supports a LSM6DS0 chip which is a 6dof(degree of freedom) IMU(Inertial Measurement Unit) featured with triaxial accelerometer and triaxial gyroscope, supports different modes of configuration. To configure the IMU refer to the "Extension Unit API" document.
 
1.5 What is the calibrated file's format?
 
The camera is calibrated using OpenCV. The calibrated files are in the yml format.
 
1.6 What are the output formats supported in the Tara Camera?
 
Tara supports two formats (Y16 / RGB24).
  • In Y16 (8bpp) format the Pixel arrangement :
  • Byte 1 - M9 M8 M7 M6 M5 M4 M3 M2
  • Byte 2 - S9 S8 S7 S6 S5 S4 S3 S2
  • In RGB24(10bpp) format the Pixel arrangement :
  • Byte 1 - X X X X M1 M0 S1 S0
  • Byte 2 - M9 M8 M7 M6 M5 M4 M3 M2
  • Byte 3 - S9 S8 S7 S6 S5 S4 S3 S2
Also note Key - X - Don' care , M - Master , S - Slave.
 2. Tara SDK
 
2.1 What is Tara SDK?
 
  • Tara Software Development Kit (SDK) package is built on OpenCV(opencv-3.1.0) Image Processing Library is bundled with Tara - Stereo Vision USB 3.0 Camera.
  • SDK currently uses C++ API's of OpenCV, hence the applications are written in C++.
  • Tara SDK includes the commonly used stereo camera functions such as disparity, depth measurement, etc.. and few real time applications implemented in OpenCV.
 
2.2 How to install the SDK?
 
Tara SDK Installer package will be available with Tara deliverables. Follow the procedure in the document named "TaraSDKInstallation_Windows.pdf" for Windows OS.
Watch getting started with Tara SDK video at

For Linux, follow the procedure in "TaraSDKInstallation_Linux.txt" file

 
2.3 What are the applications provided in the Tara SDK Package?
 
Detailed explanation on all the applications named below are given in the document
Tara_SDK_Windows_User_Manual / Tara_SDK_Linux_User_Manual.
  • Face Detection
  • Height Measurement
  • Volume Estimation
  • Tara Camera Viewer
  • Tara Depth Viewer
  • Tara Disparity Viewer
  • Point Cloud
  • IMU Application
 
2.4 What are the platforms and OS supported by the SDK?
 
SDK are given as separate package for Linux and Windows.
OS 32 Bit 64 Bit
Windows 7 Yes Yes
Windows 8 Yes Yes
Windows 8.1 Yes Yes
Windows 10 Yes Yes
Linux 14.04 Yes Yes
 
2.5 Does the SDK come with the source code?
 
Yes, the Tara SDK package comes with the source code.
 
2.6 What is the Disparity algorithm used in the SDK?
 
SDK supports two algorithm for computing the Disparity,
  • Best quality, Lower frame rate - Stereo_SGBM (Semi-global block matching) - 3 Way generic Left and Right
  • Less quality, Higher frame rate Stereo_BM (Block matching) - generic Left and Right

There is a define(DISPARITY_OPTION) in the header file which can be altered to switch between the Disparity algorithms. After changing the disparity option the source has to be built again to reflect the changes. * Default value is set to 1


Disparity Option Value Disparity Algorithm
1 Stereo_SGBM 3 Way generic Left and Right
0 Stereo_BM - generic Left and Right
 
2.7 What are the output formats supported by SDK?
 
SDK supports Y16 format. To build your OpenCV with the custom format, the source code of the OpenCV sample has to be altered.
  • For Windows, the source file is in the SDK under the Source directory (OpenCV_Patch\Windows\OpenCV 3.x.x_Source) named cap_dshow.cpp.
  • For Linux, the source file is in the Directory Source/OpenCV-Patch named cap_v4l.cpp
  • These source files at the sources\modules\videoio\src has to be replaced before building the OpenCV solution.
 
 
2.8 What is the procedure to be followed while building OpenCV?
 
The procedure to build OpenCV is specified in the document given along with the Tara SDK package.

OS Document
Linux Tara_SDK_Linux_User_Manual
Windows Building_SDK_Solutions_Windows
 
 
2.9 Is it mandatory to have OpenCV, to test the SDK samples?
 
No, the library files provided in the Tara SDK package is enough to run the applications. The executable and the library files has to be placed in the same location.
 
 
2.10 Does the SDK applications use rectified images?
 
The applications in the SDK use rectified images. Rectified such that there is only displacement in the x axis.
 
 
2.11 In the SDK, can the Exposure and Brightness of the camera altered in run time?
 
Yes, the Exposure and Brightness of the camera can be altered. On the image window of the application
  • Press 'e/E' to change the exposure. Exposure range is from (10 to 1000000 micro seconds)
  • Press 'b/B' to change the brightness. Brightness range is from 1 to 7.
 
 
2.12 Where are the documents mentioned in the FAQ found?
 
The documents are found after installing the SDK. There is a directory named Documents in the SDK folder structure, where all the documents are placed. Please watch our video on getting started with Tara SDK.
 
 
2.13 How to resolve the error "Failed Reading Intrinsic and Extrinsic Files" while executing the sample applications in the Tara SDK?
 
  • Intrinsic and Extrinsic Files are the calibration files which are in the camera flash, it will get loaded automatically when you execute the application.
  • You have to run the applications as administrator if you have installed the SDK in C Directory or else give Full control to the bin folder of the SDK in C Directory.
  • To avoid this you can install them in some other directory, where the application can be run in user mode.
Note: Please refer to section 9 Error Cases in "Tara_SDK_Windows_User_Manual.pdf" document, where few common issues and their solutions are discussed.
 
 
2.14 How to overwrite the calibration data pre loaded in the camera flash?
 
Writing your calibrated files to the flash will override the pre-calibrated data and also you will no longer have access to the pre calibrated data. We generally do not recommend to overwrite the data in the camera flash.
 
  3. Reference Design - HW
 
3.1 What does e-con Systems' reference design provide for developers and OEMs?
 
Tara is a UVC Complaint 3D Stereo camera based on MT9V024 stereo sensor from ON Semiconductor. The reference design is self-contained and is provided with Tara SDK. This enables the developers to start their application development on our stereo camera reference design from the day one. OEM's can customize this stereo camera hardware and integrate this in to their systems or even license this stereo camera design from e-con.
 
3.2 How do we know that the cameras are perfectly in Sync? Is there any metrics to detect how closely the Sync is?
 
The CMOS image sensors used in this Tara camera are from ON Semiconductor and support external synchronization and e-con's design ensures that the left and right sensors are operated synchronously. The application receives the WVGA images at 30fps from each left and right camera (Total of WVGA @ 60fps) which are exposed exactly at the same time. There is no metric to define the synchronous nature, but the synchronous nature can be demonstrated with accurate stop watch or similar objects.
 
3.3 What is the camera sensor that is used in the Tara reference design?
 
The sensor used in the reference design is MT9V024 (monochrome) from ON Semiconductor.
 
3.4 Can the camera support color?
 
The current version of stereo camera does not support color. Only monochrome sensors are supported now.
For color Stereo camera contact sales@e-consystems.com
 
3.5 What is the shutter type on the sensor?
 
The sensor is global shutter sensor and the MT9V024 sensor is operated in Global Shutter mode in our reference design.
 
3.6 What is the lens mount used?
 
The lens mount used in the Tara Camera reference design is S-mount M12 lens holder (M12 P0.5 lenses are supported by default). e-con can customize this camera for other lens mounts as well as other baseline. The baseline refers to the distance between the left and right cameras and this can also be customized.
 
3.7 Can I change the lens mount from S mount to C mount?
 
Yes, we can customize the stereo camera to support C/CS mount lens.
 
3.8 Where can I get the datasheet of the lens?
 
Please contact e-con sales team to get the lens datasheet.
 
3.9 The MT9V024 is a small resolution sensor and I would like to integrate OV5642 since it as 5MP. Along with the depth, I also want to shoot a picture. Can I have a different sensor integrated other than the MT9V024?
 
The MT9V024 sensor support external synchronization input with Master/Slave support. The OV5642 does not support this feature and hence synchronous capability cannot be demonstrated on the OV5642 sensor.
 
3.10 I would like to buy my own lens instead of the lens provided by e-con Systems. Is this possible?
 
The lenses are chosen after considering various parameters and then calibrated using the calibration software developed by e-con using OpenCV. If you try to use any other lens or if you have done any modifications to the lens set up provided in the e-con Stereo camera, then you must calibrate the new lens or new lens position. For the stereo camera analysis, the calibration is the crucial process and the calibration accuracy determines the overall accuracy of the stereo camera system. The calibration is easily lost, even with the slightest change in the lens position. If you use your own lens, then you must do the calibration thoroughly before moving on to next task.
 
3.11 What is the pricing of this reference design?
 
Please visit www.e-consystems.com/webstore.asp for more information.
 
3.12 I would like a camera board with a different base line. Can e-con do that?
 
The base line of the camera board can be customized. Please contact sales@e-consystems.com
 
3.13 I would like to buy Tara with a different lens. Whom should I contact?
 
Please contact sales@e-consystems.com The lens used in Tara can be customized based on the customer need.
  4. Reference Design - SW
 
4.1 What are the sample applications provided along with this reference design kit?
 

A SDK is given along with the Tara Camera.

  • Tara Software Development Kit (SDK) package is built on OpenCV(opencv-3.1.0) Image Processing Library is bundled with Tara - Stereo Vision USB 3.0 Camera.
  • SDK currently uses C++ API's of OpenCV, hence the applications are written in C++.
Tara SDK includes the commonly used Stereo camera functions such as disparity, depth measurement, etc.. and few real time applications implemented in OpenCV.
 
4.2 I understand that e-con Systems' provides sample depth measurement applications along with the kit. What is the number of bits/pixel information that is provided?
 
The depth map is calculated from the disparity map computed from the left and right images. The calculated depth map is 8bits per pixel.
 
4.3 Can I get the source code of this application?
 
The source code for the sample applications are provided as part of the software package when you buy the complete Stereo Camera Reference design kit from e-con.
 
4.4 Can the working distance be varied? If yes, how?
 
This requires choosing different lens and also calibrating the camera for the new lens. Refer question 4.5 also.
 
4.5 I want to have the depth measurement from 1-10 meters. Can it be done?
 
This may not be possible, as at 10m distance, the disparity seen on the sensors may be too small to detect the depth. This requires changing the distance between two cameras. e-con can do the integration for the same.
 
4.6 What is Calibration? Why should I do that?
 
Camera images usually contain small amount of spherical distortion known as goldfish eye bowl effect. Especially linear featured items like straight wooden or steel bar, door edges appear to be round edged at image edges. Stereo camera calibration has to be done in-order to determine nature of distortion and to relatively reduce error further. Calibration can be done by training camera to observe test patterns like chess board, spots, lines or squares. The task of camera calibration is to determine the parameters of the transformation between an object in 3D space and the 2D image observed by the camera from visual information (images). The transformation includes
  • Extrinsic parameters (sometimes called external parameters): orientation(rotation) and location (translation) of the camera, i.e., (R, t);
  • Intrinsic parameters (sometimes called internal parameters): characteristics of the camera, i.e., (α,Β,γ, u0, v0).
These parameters can further be used to acquire the knowledge of depth information of an object in the stereo system.
 
4.7 Is there any way that I can just use the reference design directly without making any Calibration? I find it too long a process.
 
Yes, the calibration is a lengthy process and requires patience. The development kit comes with precalibrated set up. If the lens and camera are not adjusted, then there is no need for recalibration. If there is any change in the lens, even a slight movement of the lens thread may cause calibration data to be invalid. Then the developer has to calibrate it again.
 
 
4.8 I would like the lens to be fitted in and sent to me so that everything is calibrated and I don't need to do calibration when I get them. Is this possible?
 
The lens comes fitted in the camera development kit. As long as the lens is not moved or adjusted, the precalibration data works fine. In any case, if the developer finds erroneous results, he has to calibrate it again.
 
 
4.9 Can I get the depth of each and every pixel in the depth measurement application?
 
Yes, use the TaraDepthViewer application in the SDK, where the depth of the point selected by the user is displayed.
 
 
4.10 What is the maximum resolution that can be captured? What is the frame rate at this resolution?
 
The resolution is WVGA@60fps (left and right combined).