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Author Topic: Forest Pack Crash when adding surfaces  (Read 955 times)


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Forest Pack Crash when adding surfaces
« on: August 26, 2021, 10:02:15 AM »

I've also mailed support concerning this but I need an answer quite fast so I'll try my luch here as well.

I've encountered this problem a few times already, but I can't seem to resolve it this time.

I have uploaded the scene to wetransfer and send you the link.

In the scene you will have one forest pack, if I try to add another one of the surfaces to the forest pack or even duplicate it and replace the surfaces to the pack it crashes. I don't know what's wrong because I've used this preset to cover areas that were the same size or bigger than this. I've tried to recreate the surfaces thinking that something is wrong with them but I can't put my finger on it. I've tried resetting Xform, checking normals and whatnot but this time nothing seems to be working.

Could you please take a look and tell me what's wrong. I have latest max 2022, latest FP and latest Vray. But I also had this with lower versions on Max 2020.
« Last Edit: August 26, 2021, 11:44:42 AM by VIZIOEN »


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Re: Forest Pack Crash when adding surfaces
« Reply #1 on: August 26, 2021, 10:42:59 AM »

Crash is caused by the Collisions feature. Scattering area is too dense, and Forest cannot allocate the data structures to compute it.
Although the total number of items is not very high, there is a lot of empty space between the grass areas, which must be evaluated as well (red bounding box in the image).

If surface is planar, i suggest to assign individual area splines to Forest (one for each small area), and not use any surface at all.
Not only Splines are more efficient than Surfaces, but also in this case there is a noticeable improvement, if Forest doesn't need to evaluate the empty space between them.

When surfaces are not planar, i suggest to combine both: small spline areas to define the scattering limits, and surfaces just for elevation ('Surface Area' in Areas rollout must be off).
In this way, items are scattered using the splines, and in a second step are aligned over the surface. Even in this case, several smaller surfaces are more efficient than an unique large surface (when there are empty spaces between them).

Also if possible we suggest to disable Collisions checking, and use only when strictly necessary. It's a feature with a huge performance hit, both in CPU and memory.

« Last Edit: August 26, 2021, 11:03:25 AM by iToo »
Carlos Quintero
iToo Software


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Re: Forest Pack Crash when adding surfaces
« Reply #2 on: August 26, 2021, 11:44:56 AM »
Thank you Carlos, can confirm this works.