Simulating a LIDAR pointcloud look in C4D
In short: I'm looking to create something that looks like LIDAR scanned pointclouds, from C4D geometry scenes.
I have in the past dabbled with the LAZpoint plugin but it was cumbersome and seems to not be supported anymore for recent versions of C4D.
There are some things that I'm trying to achieve here:
I'm really looking for the 'occlusion effect' from having 'shadows' from the LIDAR scanner. This incompleteness of the scan caused by foreground object shadowing the background.
I'd like to be able to bake some colour or ambient occlusion from the model into the particles.
Render in Redshift due to other elements used in the scene.
For now I'm tinkering with a TP matrix object to generate particles.
So I have a simple scene, and populate the geometry with particles using the matrix object. I generate simple point instances.
Using the Redshift Object tag I make the source geometry invisible to the camera, but leave cast shadows on so that when I put lights in the scene (to simulate the LIDAR scanner) only the particles that catch light are visible.
Once I enabled backlighting translucency in the Redshift material for the particles, I get a good start on what I'm trying to achieve. The downside is that I'm generating huge amounts of particles that remain invisible because they're shadowed. But the upside of this is that I can quickly move some lights around to explore how I want to light the scenes without having to regenerate particles.
However, I'm looking for some advice:
I'd really like to have the particles inherit some of the color of the source objects. I figured I could use the Shader Effector for this like so:
But it looks like this doesnt' work with putting an AO effect in the color channel of the material. And it seems to work fine with matrix objects but not with particles.
Ideally I'd render as blips without size, but if I get really close to an object now - the dots become circles.
Or is there an entiry different solution to this that I should explore?
Thanks in advance.
I'm on C4D R2023 with everything up-to-date.
Dr. Sassi last edited by Dr. Sassi
It is pretty simple, create the object you like to "LIDARize" and create a camera where the LIDAR scan would have been. Then create a 360º rotation animation of its view, preferably as a 10mm focal length camera.
I would suggest connecting all objects in a single copy. Increase the points if needed (Subdivide) and go into point mode.
The selection tool must be in Visible Points, preferably in Rectangle Mode. Now select all the points visible from that Point Of View (POV). Since your camera is animated, move the time slider to the following view. Shift the key down and select more points. Since you select only the visible points, that is precisely what the LIDAR scanner would have seen.
Continue so you get one time around.
This needs to be in a Point selection.
The model goes into an RS Matrix, and the Particles are set to Point. Adjust the size accordingly. Place the Point selection into the Matrix after setting it to Vertex.
The RS Matrix is provided with a Shader Effector. Use the channel you have for the Texture (Standard Material!). This will read the colors for you.
Perhaps use a Random Effector, as some noise will be in the point position.
Anything else is in the file:
Render, and again, adjust the point size. Perhaps add some RS Post Bloom.
Hi Sassi, thanks!
I was indeed thinking along similar lines - although I'm complicating things a little further by using lights to reveal certain areas (basically generating lots of dots, but only seeing the ones that are lit).
I'm getting pretty close to the base of the look that I'm going for. However the particles have real-world dimensions which means that the foreground particles show up as spheres/circles rather than dots.
Is it possible to scale the particles relative to distance to the camera? Maybe using Xpresso?
Ah - parenting a PLAIN effector (with scale set to -1) with a spherical field to the camera does the trick!
Dr. Sassi last edited by
Sounds like you got everything you need. Thank you very much for updating your own question.
My best wishes for your project