Procedure for voxel generation

[purugupta99]

Can you share the procedure for generating the voxels(.mat file) from the mesh files? I'm trying to generate similar dataset to be used for training MeshRCNN.
TIA

[xingyuansun]

Hi,

Thank you for asking! We previously used some MATLAB code to generate voxels from mesh grids. Unfortunately, it is difficult for me to access the code after moving to Princeton. However, you may still use tools like binvox to voxelize meshes. Thank you!

Best,
Xingyuan

[purugupta99]

Hi @xingyuansun
I tried using binvox, but facing following issues:-

1. I am converting .binvox files to .mat files using scipy and having problems with the orientation of object in the .mat file
2. I am not able to get the R|t matrix of the camera in viewvox, viewvox is the file provided by the creator of binvox to view the .binvox file
   PFA the attached sample images from viewvox(.binvox file) and the .mat file respectively :-
   
   

[ZZWENG]

Hi, @purugupta99 I am going through the same procedure and am wondering if you figured it out? My obj file had xyz range of [-1, 1] but the coordinates stored in the binvox files have range approximately in [0, 256]. Is there any scaling we need to do before feeding the obj to binvox, or is there a way to get the R, T matrices?

Edit: Nevermind, I figured it out.

[bluestyle97]

Hi, @ZZWENG , I'm facing the same issue, could you please kindly teach me how you figure it out?

[bluestyle97]

Hi, @purugupta99 , could you please tell me what program you are using to visualize the binvox files as in the upper picture?

Edit: It is viewvox, I ignore that, nervermind.

[ZZWENG]

Hi, @ZZWENG , I'm facing the same issue, could you please kindly teach me how you figure it out?

I am not sure what your use case is, so it may not be applicable to you. For me, I first convert all .obj files to .binvox files

ls path/*.obj | xargs -n1 ./binvox -d 128

And then, I used binvox_rw module to convert .binvox to .mat, and then used meshrcnn's utilility function to load the .mat file.

import binvox_rw
from scipy.io import savemat
model = binvox_rw.read_as_3d_array(open(binvox_fname, 'rb'))
voxels = model.data.astype(np.int).transpose(0,2,1)
voxels[:, 1, :] = -voxels[:, 1, :]
savemat(mat_fname, {'voxel': voxels})

from meshrcnn.utils import shape as shape_utils
my_voxels = shape_utils.read_voxel(mat_fname)

[bluestyle97]

Hi, @ZZWENG Thanks a lot for your kind reply! I'm trying to train meshrcnn on a custom 3D model dataset too. Could you please explain why you did these two operations when converting .binvox to .mat? Is them essential and what do they mean?

voxels = model.data.astype(np.int).transpose(0,2,1)
voxels[:, 1, :] = -voxels[:, 1, :]

[ZZWENG]

Hi, @ZZWENG Thanks a lot for your kind reply! I'm trying to train meshrcnn on a custom 3D model dataset too. Could you please explain why you did these two operations when converting .binvox to .mat? Is them essential and what do they mean?

voxels = model.data.astype(np.int).transpose(0,2,1)
voxels[:, 1, :] = -voxels[:, 1, :]

I remember doing that while I was trying to replicate a pix3D voxel file using its .obj file. Maybe it is not necessary for you.

[bluestyle97]

I find it is a rotation of the coordinate system which was done in Pix3D, thank you very much!

…

2020年10月16日 上午12:36，Jen Weng ***@***.***> 写道： Hi, @ZZWENG <https://github.com/ZZWENG> Thanks a lot for your kind reply! I'm trying to train meshrcnn on a custom 3D model dataset too. Could you please explain why you did these two operations when converting .binvox to .mat? Is them essential and what do they mean? voxels = model.data.astype(np.int).transpose(0,2,1) voxels[:, 1, :] = -voxels[:, 1, :] I remember doing that while I was trying to replicate a pix3D voxel file using its .obj file. Maybe it is not necessary for you. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#19 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE5N4ZIFAWMJNVSUW7XKP3LSK4QJTANCNFSM4PKPW2CA>.

[jiayaozhang]

@bluestyle97

Hi, I know how to get the voxel.mat then, but i have a question about how to get the rot_mat and trans_mat ?
Can you help me?

[H19012]

Does anybody know the way to convert .mat to .binvox?