Small holes in Terrain

[cyphyr]

Hi Gang

I'm trying to find a solution to finding small holes in my terrain. More specifically I have found that the Strata and outcrop shader is making small vertical slits when it has any further displacements applied to it. I'm not sure if this is a new bug (prolly not), but I don't thing this is an example of extreme displacement or maybe I'm just so used to the standard stuff now I don't see this as particularly extreme...
Thanks in advance you stunningly talented lot

Richard

Attached image rendered at 0.75, 11

PS: already tested that the holes are NOT caused by the "small displacements" in the surface layer...
PPS: also tested removing everything apart from the Terrains PowerFractal and the Strata and Outcrop, still has holes

[PorcupineFloyd]

Same thing happens when importing .ter files from other software with "fractal detail" applied. I believe it has something to do with displacement blending (or rather lack of it).

[EoinArmstrong]

Ah - that explains it for me too.

In my latest pic, I had to clonebrush out 10-15 single-pixel anomalies (all showing the sky colour) in my mountain.

[cyphyr]

Yeah I could clone out the holes but I'd really rather not. Also this makes animation almost impossible ...
Richard

[cyphyr]

In the Compute Terrain a small patch size (default size 20 down to 2) and tick in "Smooth Surface" seems to have sorted almost all the holes
Richard

ps I'm thinking this is not a general solution, it may depend on terrain type, number of octaves and patch size ...

[PabloMack]

In the Compute Terrain a small patch size (default size 20 down to 2) and tick in "Smooth Surface" seems to have sorted almost all the holes Richard
ps I'm thinking this is not a general solution, it may depend on terrain type, number of octaves and patch size ...

I am having the same problem. It seems it only happens on steep cliff sides created with a heightfield. The holes in my terrain are pretty bad. Cyphyr's solution seems to have improved things substantially. I'll have to redo a six day render to correct all images, though.

[Matt]

Go to the internal network of the render node and edit the "Render subdiv settings" node. Enable "Force all edges". This will likely fix most, if not all, of the holes on steep displacements. It will increase render times because it adds more microtriangles on the steep displacements, but it also adds more detail in these areas. To keep render times down you could reduce the overall detail in the Quality tab. Now that there's more detail on the steep displacements you might find that you don't need the same detail level you had before.

Matt

[mhaze]

I don't have any internal setting in my render layer? how do I get them please.

[Oshyan]

[EDITED - Matt]

Copy and paste this into your Renderer node's *internal* network.

<terragen_clip>
   <render_subdiv_settings
      name = "Render subdiv settings 01"
      gui_use_node_pos = "1"
      gui_node_pos = "1160 -60 0"
      gui_group = ""
      fully_adaptive = "1"
      force_all_edges = "1"
      jitter_shading_points = "1"
      ray_detail_multiplier = "0.25"
      stabilise_ray_detail_in_motion = "0"
      ray_detail_stabilisation = "3"
      >
   </render_subdiv_settings>
</terragen_clip>

- Oshyan

[Tangled-Universe]

Hi Oshyan/Matt,

Just FYI, my "Inside Deep Forest" scene you have for testing purposes is a good one for assessing these kind of issues and if I recall correctly the proposed fix above does not work completely/satisfactory on this scene.

Richard, remember you had this issue before? With holes in your terrain showing up in Z-depth AOV? This should fix it, but I think I've put the same info in that particular topic. So if you feel up to reviving that project, now/soon could be the time.

Keen on seeing your strata work, creating rocky stuff in TG is still one of the most fun stuff to do

Cheers,
Martin

[PabloMack]

Go to the internal network of the render node and edit the "Render subdiv settings" node. Enable "Force all edges".

Hmmm...It was already enabled.

[attach=1]

[Matt]

I've edited Oshyan's reply with the subdiv settings. In my reply I was suggesting to turn "Force all edges" on while I expected "Fully adaptive" and "Jitter shading points" would already be on. My comments about render time and detail assumed they were all on. However, we do often suggest that you turn "Fully adaptive" and "Jitter shading points" OFF if you are rendering an animation, so that's where Oshyan's clip came from. That's also what happens when you run the "Animation Check" on the Sequence tab.

Turning "Fully adaptive" off reduces detail on steep displacements and therefore reduces render time, but it is usually more stable in animations.

Matt

[Matt]

Go to the internal network of the render node and edit the "Render subdiv settings" node. Enable "Force all edges".

Hmmm...It was already enabled.

In that case maybe there is some other cause of the holes in your render. Can you send us something to test?

Matt

[PabloMack]

In that case maybe there is some other cause of the holes in your render. Can you send us something to test?

I want to reiterate that Cyphyr's "fix" have gotten rid of most of the holes. Here is an animation without the "fix". The sky and lake behind the mesa show through the steep cliffs. They are mostly on the left side of the mesa. Stop the animation at 0:20 and there is a hole near the foot of the mesa.

http://www.youtube.com/watch?v=VEY6dPfmwrk

I have stripped the millions of plants out of the project which made it extremely sluggish. Gone are all but one camera and one renderer. I have also undone Cyphyr's fix and the holes are visible on frame 1 of the animation. I have zipped up this version and included the hieghtfield I am using. If you provide me with an email address (either here in the forum or with my email address you have on file), I will sent it to you.

Thanks.

[cyphyr]

Hey a blast from the past. Good to see that some old topics can be usefully raised from the grave
I'll take a look at my old project (if I can find it !) when I get back infront of my PC next week sometime