Downloaded the video from vimeo and made a snapshot per frame of the debug view.
I see a lot of triangle clusters occasionally lodding up and down. It's not obvious what triggers the change - seems neither camera distance or curvature at incident angles.
I have not found adjacent clusters that do a transition. Only 'isolated' clusters, meaning a cluster that goes from lod 0 to lod 1 is surrounded only by lod 0, but never both 0 and 1.
This leads me to some speculation of a very simple system, assuming we would want to go from lod 0 to lod 2:
The whole model can transit between two lods, but not more. It becomes an entire different model if that would be necessary. So no hierarchy necessary at lower level of the tech.
After all clusters have changed from lod 0 to 1, all cluster boundaries have detail that matches still lod 0. So there might be a second phase of transition that changes the boundaries to lod 1 as well. (This second phase could be mixed with the first ofc.)
After everything is at lod 1, replace it with the version of the model that contains lod 1 and 2.
Some image showing two clusters (left yellowish / right blueish) and a common boundary path between them:
So for each cluster we get subclusters to each adjacent one (light and dark green). We can imagine the clusters as polygons (two quads) and the shared boundary path as an edge between 2 polygons.
The point is, each subcluster would have only 3 states:
All at lod 0.
Center at 0, edge at 1.
All at 1.
That's a lot simpler than a tree of edge collapses to have a progressive mesh, and it's still about efficient clusters not individual triangles of course.
Discrete LODs are already there, for both streaming and weak platfroms.
I think the idea would work for a real hierarchy to have more lods than just two for a huge model that needs this.
Splatting points could be still used additionally, e.g. clusters of points per vertex of the clusters.
(wanted to upload two screenshots but did not work, try again in a new post...)
Upload worked after cropping the images. Going through the video frame by frame shows the clusters much better.
I see a lot of triangle clusters occasionally lodding up and down. It's not obvious what triggers the change - seems neither camera distance or curvature at incident angles.
I have not found adjacent clusters that do a transition. Only 'isolated' clusters, meaning a cluster that goes from lod 0 to lod 1 is surrounded only by lod 0, but never both 0 and 1.
This leads me to some speculation of a very simple system, assuming we would want to go from lod 0 to lod 2:
The whole model can transit between two lods, but not more. It becomes an entire different model if that would be necessary. So no hierarchy necessary at lower level of the tech.
After all clusters have changed from lod 0 to 1, all cluster boundaries have detail that matches still lod 0. So there might be a second phase of transition that changes the boundaries to lod 1 as well. (This second phase could be mixed with the first ofc.)
After everything is at lod 1, replace it with the version of the model that contains lod 1 and 2.
Some image showing two clusters (left yellowish / right blueish) and a common boundary path between them:
So for each cluster we get subclusters to each adjacent one (light and dark green). We can imagine the clusters as polygons (two quads) and the shared boundary path as an edge between 2 polygons.
The point is, each subcluster would have only 3 states:
All at lod 0.
Center at 0, edge at 1.
All at 1.
That's a lot simpler than a tree of edge collapses to have a progressive mesh, and it's still about efficient clusters not individual triangles of course.
Discrete LODs are already there, for both streaming and weak platfroms.
I think the idea would work for a real hierarchy to have more lods than just two for a huge model that needs this.
Splatting points could be still used additionally, e.g. clusters of points per vertex of the clusters.
(wanted to upload two screenshots but did not work, try again in a new post...)
Upload worked after cropping the images. Going through the video frame by frame shows the clusters much better.
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