How you generate the depthmaps in GangnamStation?
shuimushan opened this issue · comments
Hi, I wonder how the depth maps in GangnamStation and HyundaiDepartmentStore datasets are generated. In the trajectories-txt, you mentioned images and depth maps come from a single sensor. So are the images and depth maps collected from RGBD sensors? If not, how the intrinsic params for depth sensors in sensors.txt are got?
Hello!
The depth maps were generated from the lidar scans. We accumulated lidar scans in a small window around the image timestamps and then reprojected the 3D points onto the images using the camera parameters.
Images and depth maps do not need to come from a single sensor. Could you please point me to the part of the documentation that led to the confusion? The sensor_type can be, a.o., camera or depth and for both, intrinsic parameters can be specified.
Does this answer your questions?
I see. So the depth maps are got through post processing with lidar scans. Then how the intrinsic params for each depth sensor are acquired?
We projected the lidar points onto the camera images but used a lower resolution. Thus, the depth map intrinsics are a downscaled version of the corresponding camera intrinsics.
For example:
GangnamStation/B1/release/mapping/sensors
This depth sensor,
40027089_01_depth, , depth, OPENCV, 864, 682, 570.5555443175579, 577.1324649757152, 433.9799746546102, 340.2369257807652, -0.157407343123675, 0.08784706389411968, 0.0008130076548242082, 0.0007199416321939081
is a downscaled version (1/3) of this camera.
40027089_01, , camera, OPENCV, 2592, 2048, 1711.6666329526736, 1733.0898654989219, 1301.9399239638306, 1021.7085395879869, -0.157407343123675, 0.08784706389411968, 0.0008130076548242082, 0.0007199416321939081
The sensor_id shows that they correspond to each other. Distortion coefficients do not change as they are independent of image resolution.
Thanks for your reply!