Qu Cao
Last seen: Today
MathWorks
39 total contributions since 2016I'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.
Qu Cao's Badges
Contribute at least one answer each month for 3 consecutive months
Awarded to Qu Cao on 02 Sep 2020
Answer 10 questions that were unanswered for more than 30 days
Awarded to Qu Cao on 19 Aug 2020
3 of your answers have been accepted
Awarded to Qu Cao on 13 Sep 2019
Provide your first answer ever to someone else's question
Awarded to Qu Cao on 20 Jul 2017
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...
11 jours ago | 0
| accepted
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.
5 mois ago | 0
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.
5 mois ago | 0
| accepted
Undefined function 'estimateGeomerticTransform' for input arguments of type 'SURFPoints'.
There is a typo in your code, estimateGeomerticTransform should be estimateGeometricTransform.
5 mois ago | 0
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...
8 mois ago | 0
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...
8 mois ago | 0
helperTrackLocalMap error with Monocular SLAM
Answer pasted from comments: Please try tunning the parameters to see if it helps improve the robustness: In helperIsKeyFrame,...
8 mois ago | 0
Why is the pointsToWorld back-projection inverted?
You may need to convert the camera world pose to extrinsics using cameraPoseToExtrinsics: [worldOri,worldLoc] = estimateWorld...
8 mois ago | 2
| accepted
rectangle instead of square for camera calibration
Unfortunately, this function does not support rectangle patterns.
9 mois ago | 0
How to calculate fisheye intrinsics?
You can use undistortFisheyeImage function to produce a "virtual perspective" camera intrinsics, which is the format you need. S...
10 mois ago | 1
| accepted
How can I find a diameter of cylindrical 3D point cloud in MATLAB?
https://www.mathworks.com/help/vision/ref/pcfitcylinder.html
10 mois ago | 0
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 ...
10 mois ago | 2
| accepted
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...
environ un an ago | 1
| accepted
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...
plus d'un an ago | 0
| accepted
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...
plus d'un an ago | 0
How to find union of two SURFPOINTS variables?
surf3 = union(surf1, surf2, 'rows');
plus d'un an ago | 0
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...
plus d'un an ago | 0
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.
plus d'un an ago | 0
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...
plus d'un an ago | 0
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...
plus d'un an ago | 0
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...
plus d'un an ago | 1
| accepted
What is the reference point for the orientation and location arguments of addView and addConnection functions in CV Toolbox?
In both functions, it means relative to the previous view, not the very first view.
presque 2 ans ago | 0
| accepted
Camera Calibrator Parameters and estimation errors (How to use post calibration)
Once you get the camera parameters from the App, you can use undistortImage to undistort new images if they are captured by the ...
environ 2 ans ago | 0
Wrong Documentation for pointsToWorld?
You may want to use fisheyeIntrinsics in this case.
environ 2 ans ago | 0
shouldn't the reference frame replace the frames of the subsystem
Since the Reference Frame is attached to Solid 8 not the World Coordinate, the rotating axis will be one of the Solids 8's refer...
plus de 3 ans ago | 0
glme can't deal with NaNs?
According to the error message, it seems that the error is not associated with NaN but the rank of the matrix X. You can chec...
plus de 4 ans ago | 0
How to change a multi-variable matrix with different sliders?
It might be difficult to understand your workflow without a snapshot of the GUI you are designing. One suggestion to debug t...
plus de 4 ans ago | 0
For loop inside functions in fsolve
I recommend you to provide more details about the equations you want to solve. You can also refer to the following documenta...
plus de 4 ans ago | 0
Using intel Atom as xPC target
http://www.mathworks.com/matlabcentral/answers/102370-is-matlab-supported-on-intel-atom-processor
plus de 4 ans ago | 0
Derive class from Simulink.ConfigComponent
After opening a model (any model), you can use the following code to get access to the Simulink.ConfigComponent of the model: ...
plus de 4 ans ago | 0
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