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Qu Cao

MathWorks

Last seen: 6 dagen ago Active since 2016

I'm an Automated Driving and Mapping Engineer at MathWorks and a Mechanical Engineer by education.

DISCLAIMER: Any advice or opinions posted here are my own, and in no way reflect that of MathWorks.

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Answered
About "slam" on my camera device
The example shows how to run stereo visual SLAM using recorded data. It doesn't support "online" visual SLAM yet, meaning that y...

7 dagen ago | 0

Answered
Is Unreal Engine of the Automated Driving Toolbox available on Ubuntu?
As of R2021a, only Windows is supported. See Unreal Engine Simulation Environment Requirements and Limitations.

ongeveer 2 maanden ago | 0

Answered
why we use Unreal engine when there is a 3D visualization available in Automated driving toolbox?
It's not just used for visualization. With Unreal, you can configure prebuilt scenes, place and move vehicles within the scene, ...

ongeveer 2 maanden ago | 0

| accepted

Answered
About running a stereo camera calibrator
In general, you can use any type of stereo camera and calibrate its intrinsic parameters using the Stereo Camera Calibrator. You...

3 maanden ago | 0

Answered
How to obtain optimal path between start and goal pose using pathPlannerRRT() and plan()?
Please set the random seed at the beginning to get consistent results across different runs: https://www.mathworks.com/help/mat...

4 maanden ago | 0

| accepted

Answered
Does vehicleCostmap this type of map only support pathPlannerRRT object to plan a path? Can I use another algorithm to plan a path?
You can create an occupancyMap object from a vehicleCostmap object using the following syntax: map = occupancyMap(p,resolution)...

5 maanden ago | 0

Answered
Defining a ROI for feature extraction rather than rectangle
Unfortunately, rectangle is the only type of ROI supported. As a workaround, you can define multiple ROIs in your image to cover...

5 maanden ago | 1

Answered
Monocular Visual Simultaneous Localization and Mapping Error: Dot indexing is not supported for variables of this type.
The example has been updated over the past few releases. For 20b version, please check the following documentation: https://www...

5 maanden ago | 0

| accepted

Answered
How can I store the feature descriptors for all 3D points found in Structure from Motion?
You can use imageviewset to store the feature points associated with each view and the connections between the views. You can al...

6 maanden ago | 0

Answered
How to use "triangulateMultiview" to reconstruct the same world coordinate point under multiple different views?
triangulateMultiview requires both camera poses and intrinsic parameters inputs to compute the 3-D world positions corresponding...

7 maanden ago | 0

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Answered
imageviewset() not returning an imageviewset object
imageviewset is introduced in R2020a. If you are not able to upgrade to 20a, you can use viewSet as a workaround.

11 maanden ago | 0

Answered
How to ensure that the number of matches between 2 images is equal to the number given?
You can set 'MatchThreshold' to 100 and 'MaxRatio' to 1.

11 maanden ago | 0

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Answered
Undefined function 'estimateGeomerticTransform' for input arguments of type 'SURFPoints'.
There is a typo in your code, estimateGeomerticTransform should be estimateGeometricTransform.

11 maanden ago | 0

Answered
How do I find 3D coordinates from stereo picture pair?
You can use reconstructScene function to compute the 3-D world points from a disparity map. Then, you can query the 3-D coordina...

ongeveer een jaar ago | 0

Answered
RRT navigation toolbox and automated driving toolbox also costmap from driving scenario
1) plannerRRT in Navigation Toolbox is a generic motion planner where you can define the state space. pathPlannerRRT in Automate...

ongeveer een jaar ago | 0

Answered
helperTrackLocalMap error with Monocular SLAM
Answer pasted from comments: Please try tunning the parameters to see if it helps improve the robustness: In helperIsKeyFrame,...

ongeveer een jaar ago | 0

Answered
Why is the pointsToWorld back-projection inverted?
You may need to convert the camera world pose to extrinsics using cameraPoseToExtrinsics: [worldOri,worldLoc] = estimateWorld...

ongeveer een jaar ago | 2

| accepted

Answered
rectangle instead of square for camera calibration
Unfortunately, this function does not support rectangle patterns.

ongeveer een jaar ago | 0

Answered
How to calculate fisheye intrinsics?
You can use undistortFisheyeImage function to produce a "virtual perspective" camera intrinsics, which is the format you need. S...

meer dan een jaar ago | 1

| accepted

Answered
How can I find a diameter of cylindrical 3D point cloud in MATLAB?
https://www.mathworks.com/help/vision/ref/pcfitcylinder.html

meer dan een jaar ago | 0

Answered
Function estimateWorldCameraPose() or extrinsics() for fisheyeParameters is missing. Is it possible to change these functions for fisheye?
fisheyeIntrinsics can't be used directly. Instead, you can use undistortFisheyeImage function to produce both undistorted image ...

meer dan een jaar ago | 2

| accepted

Answered
Unit of worldpoints returned by triangulate function
The unit is determined by the input stereoParams. The default world unit is mm: https://www.mathworks.com/help/vision/ref/stere...

meer dan een jaar ago | 1

| accepted

Answered
How to Transform of coordinate of actors from vehicle coordinate to world coordinate or refference coordinate system (ADAS toolbox) ...?
The following documenation page explains the vehicle coordinate system and the world coordinate system: https://www.mathworks.c...

bijna 2 jaar ago | 0

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Answered
3D Vision Toolbox - DisparityRange - what limits the range to 128 and why?
This is due to the implementation that utilizes parallel programming on multi-core processors. The following post might be hel...

bijna 2 jaar ago | 0

Answered
How to find union of two SURFPOINTS variables?
surf3 = union(surf1, surf2, 'rows');

bijna 2 jaar ago | 0

Answered
Create a cameraParameters object with more than one Intristic Matrix?
Since R2019b, you can use an array of cameraIntrinsics objects to represent the intrinsic parameters of a bunch of different cam...

bijna 2 jaar ago | 0

Answered
How can i compute depth maps from disparities maps of stereo pairs captured with a calibrated camera ?
You can use disparityBM or disparitySGM to compute a depth map.

bijna 2 jaar ago | 0

Answered
Camera looking down the negative Z-Axis
Hi Alex, In Computer Vision Toolbox we use the y-down/z-forward camera coordinate systems: https://www.mathworks.com/help/visi...

bijna 2 jaar ago | 0

Answered
Camera Pose Estimation from Non-calibrated camera images
Unfortunately, currently all the functions used in the Structure-from-Motion workflow require the camera to be calibrated. You c...

ongeveer 2 jaar ago | 0

Answered
How to limit ORB features?
Hi Helia, the selectStrongest function picks the points based on the Metric values: https://www.mathworks.com/help/vision/ref/o...

ongeveer 2 jaar ago | 1

| accepted

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