Render color images with alpha channel about pyrender HOT 13 CLOSED

Hi @mmatl , hah, I am also wondering why you did not add point_size parameter for the offscreen renderer, or you just forgot it, lol. Maybe it'd better if we can control the point size even in the offscreen mode.

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Hi @ChenXuelinCXL! Just fixed these features in c322a00.

Just set the scene's background color to have transparency (i.e. alpha = 0). Now, the offscreen render will return the full RGBA color matrix. Save it out with PIL to view it (make sure to save as a PNG).

For example:

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Sorry, had to fix a few tests. Deploying this now to PyPi as version 0.1.10.

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Hi @mmatl , wow, thank you so much! BTW, I am rendering point clouds, currently, I am trying to convert each point into a sphere mesh, so I can control the rendered point size via changing the radius of the spheres, this is obviously inefficient. So could you please tell me if there is a way to directly rendering the point clouds with the control of the point size?

Thank you!

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Yeah, absolutely! There's a simple option for this if you're okay with your points being screen-space quads.

import pyrender
import numpy as np
import trimesh

m = trimesh.creation.icosahedron()
pts = m.vertices
colors = np.random.uniform(size=pts.shape)

s = pyrender.Scene()
mn = pyrender.Mesh.from_points(pts, colors=colors)
s.add(mn)
pyrender.Viewer(s, use_raymond_lighting=True, point_size=10)

Just control the point size with that point_size parameter.

If you have a uniform-color point cloud that you want to render with spheres instead, used instanced rendering of a trimesh by specifying the poses keyword-argument.

s = pyrender.Scene()
m = trimesh.creation.uv_sphere(radius=0.1)
m.visual.vertex_colors = np.array([0.0, 1.0, 1.0])
poses = np.tile(np.eye(4), (len(pts), 1, 1))
poses[:,:3,3] = pts
mn = pyrender.Mesh.from_trimesh(m, poses=poses)
s.add(mn)
pyrender.Viewer(s, use_raymond_lighting=True, point_size=10)

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@ChenXuelinCXL Yeah, it's actually there! Just forgot to add it to the docstring -- it should be visible now: https://pyrender.readthedocs.io/en/latest/generated/pyrender.offscreen.OffscreenRenderer.html#pyrender.offscreen.OffscreenRenderer.

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I'm going to write this up in the docs. FYI, with the newest commit, it would look something like this for getting RGBA:

color, depth = renderer.render(scene, flags=RenderFlags.NONE) # Returns 3-channel color
color, depth = renderer.render(scene, flags=RenderFlags.RGBA) # Returns 4-channel color

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Hi @mmatl , big thanks for all of this! I am trying this!

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@ChenXuelinCXL no worries at all, happy you're using the code! Let me know if you have any issues.

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@ChenXuelinCXL Were you able to get it working?

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@mmatl , Yes!, After I got the latest pyrender via pip install, now I can render images with alpha channel, and render point clouds with point size control, in offscreen mode. Thank you so much for this easy-to-use code and your kindly help!

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No worries! Going to close the issue for now, feel free to open another if you run into any issues.

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