How can I export Ground Truth in KITTI format (.txt) using Ground Truth Labeler App

Hello, I am working on Lidar based 3D Bounding Box Detection. I am using matlab for labeling the ground truth data as I am working with custom dataset. However, after labeling and during export, I can only see the option export as ".mat" format. I was wondering if I can export the data as ".txt" format or at least export as ".mat format and convert it in ". txt" format later using some matlab commands. Can I do that? And if yes, How?? N.B: I am working on developing a new detection model and so, I need to benchmark my model against the SOTA models. The problem is, not all models are supported inside matlab. So, I have to manually run these detection models on my dataset with their git-hub release code which mostly follows KITTI (.txt) format ground truth labels.

Answer 1

[MathWorks Support Team]

See the example below to write a custom groundtruth export script:

https://www.mathworks.com/help/releases/R2022b/vision/ug/export-ground-truth-object-to-custom-and-coco-json-files.html?s_tid=doc_srchtitle

Also, this several Lidar models are included here: MATLAB-Deep-Learning-Model-Hub: Discover pretrained models for deep learning in MATLAB.

If you have a specific question about your workflow, please feel free to contact Technical Support.

Answer 2

[Shubham Rawat]

Hi Arghya,

Here what are you exporting as '.mat' file is of groundTruthLidar object. You can export only content of Labels and xyzCoordinates according to the properties of this object.

You may look into the groundtruthLidar object.

For converting .mat files into .txt files you may use this: https://www.mathworks.com/matlabcentral/answers/8902-from-mat-to-txt

Hope this Helps!

[Arghya Chatterjee]

Hello, thanks for your answer. It worked but I got another problem.

The way I did this was as follows:

Data = load('/home/arghya/labels.mat');
DataTruth = Data.gTruth.ROILabelData.velodyne.Car;
dlmwrite('000000.txt', DataTruth, 'precision','%.2f', 'delimiter',' ');

After writing the data to the text file, currently it looks like:

1.8 0.2 .... 180

But according to KITTI format, It should look like:

Car 1.8 0.2 .... 1.57

So, questions are now these:

1. I want to write label name along with the data(coordinates). How can I do that?

2. Is there any way to convert the last value (yaw-angle) from degrees to radians during labeling or exporting from ground truth labeler?

N.B : Say I have made 3 classes of GT objects and corresponding bounding box from lidar data (here I have shown 2 sequence) inside matlab gt labeler. So matlab stores it like:

   Time      Car Tree Pedestrian 
   0.000000  3x9 1x9      4x9
   0.117534  []  []       []

So, the 000000.txt file should look like:

Car 1.8 7.2 .... 0
Car ......
Car .....
Tree 5.6 3.5 .... 1.57
Pedestrian 3.5 5.6.... 3.14
Pedestrian .........
Pedestrian .........
Pedestrian .........

Hope this helps you to answer the question more precisely!!

[Gina Abdelhalim]

Hello Arghya Chatterjee,

did you figure it outby any chance?