The PoissonMesh Node is designed to create a polygonal mesh from the dense particle cloud created by the ParticleCloudGenerator Node. It solves the great problem of creating matching geometry for irregular shapes like trees or mountains that cannot be recreated with simple geometric primitives. However, the PoissonMesh Node is not really production-ready yet. While the foundry is working on the next round of upgrades, we can still get a good idea of how it works and what to use it for. To speed things along, I've prepared a Nuke script.
So let's go to File>Open. Select our Project Media>Lesson_04_ Media>PointCloud Nuke script, open that. And the first thing that the PointCloudGenerator Node does of course is redo the filtering calculations, and there we go! Let me get a little more screen space here. The reason I included this Nuke script is to give you a nice clean PointCloud to work with. The PoissonMesh Generator is very fussy about the PointCloud.
It has to be a smooth uniform cloud like this without a bunch of points flying all over the screen. Having said that, let's add our PaissonMesh Node. So we'll select the PointCloudGenerator Node, go to 3D>Geometry>PoissonMesh, and it immediately calculates the mesh. If we deselect, we're seeing a big flat polygonal surface which is kind of hard to see. If we select it, we get a wireframe but it's still opaque.
There is no provision of the PoissonMesh Node for a Wireframe Only display which is what I like to show you. So, with the PoissonMesh Node selected, we'll go to 3D>Modify and let's get a MergeGeo Node, simply because it does have an option here to see a wireframe. There we go! Now, I'd like to see the Particle Cloud in here. To do that, we'll have to hook the viewer up to the PointCloudGenerator Node, and there is our PointCloud. You can see that the mesh conforms to the PointCloud quite nicely.
Okay, we're done with that, we'll go back to our MergeGeo Node. Now, let's take a look at the PoissonMesh Properties Panel settings. The Use Selection button here when it finally works will allow you to select points from the PointCloud so the mesh is only built over those, but that's not yet. The Depth setting increases or decreases the density of the polygonal mesh, and it also affects the outer edge. I can show you that here. I'll select the Properties panel to turn the mesh green.
So if I lower the Depth setting from 8 let's say down to 6, watch what happens to the mesh. It loses an awful lot of the polygons, it loses density. I'll undo that to put it back to 8, so you can see a lot more polygons. Also, let me zoom out, when I put it back to 6 again, you can see the outer perimeter change shape. So Depth affects polygonal density and outer edges. Next, Scale. Scale affects how far the mesh extends beyond the perimeter of the particle cloud.
A Scale of 1.25 means it will extend 25% beyond the edge of the particle cloud. If I set the scale for example to 0.5, it's only going to use half of the particle cloud. We don't want that. Let's put that back real quick. The Solver Divide and the Iso Divide, these two settings control memory usage versus processing time. So, they have no effect on the appearance of the mesh. For the Samples Per Node, using larger numbers uses more points to create a polygon.
So you would use larger numbers if the points are noisy. That has the effect of smoothing out the mesh. For example, let's cruise in here, and I am going to set the Samples Per Node from 1 to 10, and the mesh gets smoother, and we'll put that back to default of 1, because we want to keep the detail. With our mesh built, now we can try some camera projection.
Nuke 6.3 New Features was created and produced by Steve Wright. We are honored to host his material in the lynda.com library.
- What's new in Nuke 6.3
- 3D tracking in the Camera Tracker
- Creating a cloud with the Point Cloud Generator node
- Building meshes with the PoissonMesh Generator node
- Understanding the Reconcile3D node
- Demoing the PointsTo3D node
- Introducing the Modeler node
- Aligning 2D and 3D points
- Displacing with the Displacement shader
- Adding audio
- Working with the Planar Tracker
- Working with 3D particle systems in Nuke 6.3