Custom Dataset Error

[hoangduyloc]

Hello @naurril, thanks for your great work. I have my own custom dataset (Only Lidar, No Camera), and I tried to label via your tool, everything looks good in SUS environment, but when convert label Json file to Txt KITTI file:

• I only focus on these 7 variables for each class: Center (x,y,z); 3D dimensions (heigh, width, length); and Yaw angle.
• I saw a problem is the object center position was shifted.
• I tried to test on KITTI dataset, it happends too.

So I do an simple exp: I used KITTI dataset (.bin - 0000099.bin); I converted it to (.pcd). After labeling, I converted the label to KITTI format, bellow is the result.

• The visualization in SUS env looks great

• The visulization in KITTI: Green is SUS label; Blue is KITTI groundtruth, it seem that the center location has been shifted

• So I wonder, if there is something cause that problem. Thank you.

[naurril]

Can you try to add a -height/2 offset to z-axis of the position? in KITTI format the position is the bottom center of the box. see here for reference. in this tool the position is the center of the box.

By the way this tool supports KITTI bin format

[hoangduyloc]

Hi @naurril, thanks for your fast response.

• In visualization I saw that the center was shifted not only the Z dimension, but also the X dimension. After adding the -height/2 to the Z dimension. The result looks like that.

• After adding height/2 to Z-axis, it still has the offset in X-axis

• After adding height/2 to Z-axis; and a constant 0.3 meter to X-axis, the result looks resonable https://drive.google.com/file/d/10N0FdXPWW0sbWUb4P4KoO4hGjZrmxj5_/view?usp=sharing ![Uploading Add_0,3_Offset_to_X_axis.png…]()

• So I have the wonder again; how can we find the value ~~0.3 for X-axis?; In this equation, only Z-axis was changed here. If you know how, it would be helpful for me. Thank you.

[naurril]

How did you convert the position? Is it like this Tr_velo_cam * [x,y,z-h/2]^T

[hoangduyloc]

Hi @naurril, For each object in Json file; I convert it to KITTI format, like image bellow. My dataset has no Camera so there is no Tr_Velo_Cam matrix available.

I saw the Z, and X-axis were shifted; the Z-axis seem correct now; only X-axis still wrong. Can you have a look at it? might be choose only random PC in KITTI dataset; and label it; then visualize the label again, you might see it more clearly. I'm curious too

[naurril]

visualize again with what tool？

On Wed, Sep 21, 2022, 19:58 Hoàng Duy Lộc @.***> wrote:

Hi @naurril https://github.com/naurril, For each object in Json file; I convert it to KITTI format, like image bellow. My dataset has no Camera so there is no Tr_Velo_Cam matrix available. [image: image] https://user-images.githubusercontent.com/38793688/191497296-6adb4770-b3e8-4b14-aa5b-c7c22a889a95.png

I saw the Z, and X-axis were shifted; can you try to check it? might be choose only random PC in KITTI dataset; and label it; then visualize the label again, you might see it more clearly. I'm curious too

— Reply to this email directly, view it on GitHub https://github.com/naurril/SUSTechPOINTS/issues/100#issuecomment-1253603512, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABZKCDXCGUPFCRY4DQ5NOITV7LZ4TANCNFSM6AAAAAAQQ44CI4 . You are receiving this because you were mentioned.Message ID: @.***>

[hoangduyloc]

Hi, @naurril you can try this tool - https://github.com/kuixu/kitti_object_vis

[hoangduyloc]

I make the KITTI label like that; for the alpha angle, and 2D BBoxes I add the fake values

[naurril]

with this tool，how do you set the calib content?

On Wed, Sep 21, 2022, 21:08 Hoàng Duy Lộc @.***> wrote:

Hi, @naurril https://github.com/naurril you can try this tool - https://github.com/kuixu/kitti_object_vis

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[hoangduyloc]

I copy the fake calib file via KITTI to prevent the error; but I think you dont need the calib file for only Lidar visulization

[naurril]

In kitti format, the label is represented in the camera coordinate system, the visualization tool you are using surely does the camera(fake)->lidar coordinate system conversion. if you use the fake calib, make use the Tr_velo_cam matrix is IDENTITY matrix

[hoangduyloc]

Hi @naurril, I think I figure out the problem, and thank you for clarification. It was shifted 0.27m as their setup :D ~ 0.3m I found

[naurril]

This is what Tr_velo_cam does. you are hard coding this camera-lidar transform.

[hoangduyloc]

My bad; because I have my owndata set with VLP 16 Lidar, only Lidar information, no other information so I cant do anything. Then I tried to test KITTI dataset to see if it is wrong or not; also I didnt read clearly the center of your SUS tool is Lidar or Camera Coordinates, so that is ~~. Anyway, thanks for the help.