# About SLAM initial Pose data

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Commented: Fardad on 29 Jun 2024
I am the following site
I would like to run SLAM on my stereo camera as a reference. I was able to record the left and right video with my stereo camera to inspect the first pair of images and get "stereo Params" from exporting the parameters of the stereo camera calibration app.
However, in the example of the above site, the initial camera pose is loaded from "'initialPose.mat'" and used as the function "initialPose". What should I prepare to do these on my camera device?

Qu Cao on 25 Oct 2021
The initial pose data is provided by the dataset. It's used to convert the 3-D reconstruction into the world coordinate system. If you cannot measure the inital pose of your camera, you can assume that the camera is at the origin with zero rotations:
initialPose = rigid3d(eye(3), [0 0 0])

Edited: 圭介 川邉 on 26 Oct 2021
As described above
initialPose = rigid3d (eye (3), [0 0 0])
I changed the code and ran it, but I get the following error:
Error: *
The dimensions for matrix multiplication are incorrect. The number of columns in the first matrix matches the number of rows in the second matrix
Please make sure that. Use'. *'To perform elemental multiplication.
Error: helperReconstructFromStereo (line 26)
xyzPoints = xyzPoints * currPose.Rotation + currPose.Translation;
Error: stereoslam (line 37)
[xyzPoints, matchedPairs] = helperReconstructFromStereo(currILeft,
currIRight ...
I'm using my code and properties like this, but I'm not sure why this error occurs so please let me know.
code:
currFrameIdx =1;
imshowpair(currILeft,currIRight, 'montage')
rng(0);
initialPose = initialPoseData.initialPose;
focalLength = [387.777 387.777];
principalPoint = [257.446 197.718];
baseline = 0.239965;
intrinsicMatrix = [focalLength(1), 0, 0; ...
0, focalLength(2), 0; ...
principalPoint(1), principalPoint(2), 1];
imageSize = size(currILeft,[1,2]);
cameraParam = cameraParameters('IntrinsicMatrix', intrinsicMatrix, 'ImageSize', imageSize);
intrinsics = cameraParam.Intrinsics;
[currILeft, currIRight] = rectifyStereoImages(currILeft, currIRight, stereoParams, 'OutputView','full');
scaleFactor = 1.2;
numLevels = 8;
[currFeaturesLeft, currPointsLeft] = helperDetectAndExtractFeatures(currILeft, scaleFactor, numLevels)
[currFeaturesRight, currPointsRight] = helperDetectAndExtractFeatures(currIRight, scaleFactor, numLevels)
maxDisparity = 48;
[xyzPoints, matchedPairs] = helperReconstructFromStereo(currILeft, currIRight ...
currFeaturesLeft, currFeaturesRight, currPointsLeft, currPointsRight, stereoParams, initialPose, maxDisparity);
properties:
stereoParams =
properties of stereoParameters:
Parameters of Two Cameras
CameraParameters1: [1x1 cameraParameters]
CameraParameters2: [1x1 cameraParameters]
Inter-camera Geometry
RotationOfCamera2: [3x3 double]
TranslationOfCamera2: [-138.2614 0.1132 -1.9609]
FundamentalMatrix: [3x3 double]
EssentialMatrix: [3x3 double]
Accuracy of Estimation
MeanReprojectionError: 0.7208
Calibration Settings
NumPatterns: 13
WorldPoints: [54x2 double]
WorldUnits:'millimeters'
estimationErrors =
properties of stereoCalibrationErrors:
Camera1IntrinsicsErrors: [1x1 intrinsicsEstimationErrors]
Camera1ExtrinsicsErrors: [1x1 extrinsicsEstimationErrors]
Camera2IntrinsicsErrors: [1x1 intrinsicsEstimationErrors]
RotationOfCamera2Error: [0.0012 0.0021 2.9278e-04]
TranslationOfCamera2Error: [0.1338 0.1060 0.4320]
General properties:
Name:'leftframe.avi'
Path:'C: \ Users \ 18044 \ Documents \ gitHub \ ZED SDK \ zed-matlab \ matlab'
Duration: 5.6667
CurrentTime: 0
NumFrames: 170
Video Properties:
Width: 1920
Height: 1080
FrameRate: 30
BitsPerPixel: 24
VideoFormat:'RGB24'
General properties:
Name:'rightframe.avi'
Path:'C: \ Users \ 18044 \ Documents \ gitHub \ ZED SDK \ zed-matlab \ matlab'
Duration: 5.6667
CurrentTime: 0
NumFrames: 170
Video Properties:
Width: 1920
Height: 1080
FrameRate: 30
BitsPerPixel: 24
VideoFormat:'RGB24'
currFeaturesLeft =
properties of binaryFeatures:
Features: [1000x32 uint8]
NumBits: 256
NumFeatures: 1000
currPointsLeft =
1000x1 ORBPoints Array Properties:
Location: [1000x2 single]
Metric: [1000x1 single]
Count: 1000
Scale: [1000x1 single]
Orientation: [1000x1 single]
currFeaturesRight =
properties of binaryFeatures:
Features: [1000x32 uint8]
NumBits: 256
NumFeatures: 1000
currPointsRight =
1000x1 ORBPoints Array Properties:
Location: [1000x2 single]
Metric: [1000x1 single]
Count: 1000
Scale: [1000x1 single]
Orientation: [1000x1 single]
Sheraz Shamim on 14 Jun 2023
I am having a same error. xyzPoints is empty and got same error.
And I cann't fint the "helperReconstructFromStereo" in the folder of "StereoVisualSimultaneousLocalizationAndMappingExample"!

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