External mesh vs dummy vs model

[Pikadili89]

Hi guys,

I am using SketchUp and as always there is a problem with heaviness of the model while working in it, especially if there are complex and detailed vegetation models, so my question is:

Are external mesh, dummy and original model itself same in terms of memory usage for Indigo? Lets take example of some 200MB SketchUp model of some tree.

So if I render straight out of model, will it be same for Indigo in terms of memory usage and rendering time needed as if I make external mesh of that tree and use it in model?

It happened to me that there is simply not enough memory and I get memory allocation failure if I use several such trees of 100-200MB in exterior scene. Would it help if I use external mesh process or is it the same?

Many thanks in advance!

[Yiqin]

Pikadili89,

I've not done any actual tests to compare memory usage but the use case for external meshs and proxymeshes in most 3d apps is to reduce the load in your 3d app while you are working on a model, since all the geometry is present in the rendering engine at time of render then it must all be accounted for in Indigo or whatever other rendering application you use (in terms of geometry and textures). Indigo can handle far more geometry and textures than sketchup can. Another side note is that I've been more likely to hit a memory limit by having extremely high resolution output + super sampling than I am by the scene's size/complexity so take a look at your other render settings if you are hitting a memory limit in indigo. Also if your using a massive HDRI map that could be causing problems too.

That said, many rendering apps (i believe including indigo) can efficiently make use of repeated components (instances/proxies) in a model when they are repeatedly used where the geometry for a model isn't being loaded for each individual instance of that geometry on screen. This works great for density and variety when you use the built in scatter tool to apply random transforms (scale, rotation) to the plant models and at the same time should help with reducing render resource requirements than using many different plant models to provide variety. (you can manually place, scale, and rotate instances/components as well, this works with proxy meshes too)

Also note that when using GPU rendering the amount of vram you have may be a limiting factor. If your project is too large for your gpu's vram you may have to run it on CPU rendering instead (assuming you have enough ram). And yes generally speaking for the same resolution output the more geometry + lights in a scene (plants, objects, especially lighting sources) the longer it can take for that scene to render to an acceptable clarity.

hope some of that helps, good luck!

[Pikadili89]

Yeah I got it, but I did a test and to be fair, using external mesh helps a lot in reducing memory usage. I don't know how it works but external mesh have multiple times less MB in files. So attached are files, images 1 and 2 show .skp file of external mesh component and folder of actual .igs meshes.

Image 3 show how heavy is actual .skp model of the tree and corresponding dummy which is ofc almost nothing, maybe dozen KBs.

So external meshes folder and .skp of external mesh component are combined about 15MB while .skp file of a tree is 63MB. When tested, indigo also starts fairly faster with external meshes than with original model and dummy.

Hope other SketchUp users find this useful

Cheers!

[Yiqin]

My bad, I thought you were talking about memory as in system RAM or GPU Vram not storage space. Out of curiosity when you render your file in indigo does indigo use the same amount of system or GPU memory when it renders the sketchup model that contains the plant as it does when it renders the sketchup model with the external geometry linked? My guess is that it will be the same or very close...

Yea, to know why files are bigger/smaller in terms of storage space you'd have to know how Sketchup saves it's geometry (I don't know but I do know OBJ files have always been smaller/more efficient space wise and tend to load faster in other modeling apps).

As for loading quicker at render time I think obj model formats are simply easier to read and import for Indigo and it doesn't have to unpack/uncompress all the geometry. I think, but am not certain that Indigo can use OBJ geometry natively without converting it.

As a side note Skp files are one of the few, if not only, 3d model file format that packages texture files in with the geometry. That makes it great for transporting and archiving the file as texture links don't get messed up but adds to the file size and can lead to unnecessary duplication of textures when importing exporting related models that share the same textures.

[Pikadili89]

Sorry I am not checking Indigo forum so often. Actually it uses much less system RAM and GPU Vram when rendering external mesh than when using original model file/dummy.

So before I was also using transmutr to lower the file sizes of plants but in order to be remotely usable I had to lower geometry by 75% or even 95%, this of course decimated the model. Than I created dummy for so much simplified model and used it in scenes. Even then I couldn't import more than like 5-10 bigger plants.

Now I barely reduce file size or at least to extent where it doesn't remove petals and leafs, I create external mesh and just add as much as I like.

So for everyone using SketchUp, forget dummies for plants, use external meshes.

[Yiqin]

Thanks for the update!

[Alamy]

Sorry I am not checking Indigo forum so often. Actually it uses much less system RAM and GPU Vram when rendering external mesh than when using original model file/dummy.

So before I was also using transmutr to lower the file sizes of plants but in order to be remotely usable I had to lower geometry by 75% or even 95%, this of course decimated the model. Than I created dummy for so much simplified model and used it in scenes. Even then I couldn't import more than like 5-10 bigger plants.

Now I barely reduce file size or at least to extent where it doesn't remove petals and leafs, I create external mesh and just add as much as I like.

So for everyone using SketchUp, forget dummies for plants, use external meshes.

Thanks for these great Info, I tried to make external mesh, but I didn't succeed in this, kindly explain your process as I'm also Sketchup user ... Thanks in advance

[Alamy]

Yeah I got it, but I did a test and to be fair, using external mesh helps a lot in reducing memory usage. I don't know how it works but external mesh have multiple times less MB in files. So attached are files, images 1 and 2 show .skp file of external mesh component and folder of actual .igs meshes.

Image 3 show how heavy is actual .skp model of the tree and corresponding dummy which is ofc almost nothing, maybe dozen KBs.

So external meshes folder and .skp of external mesh component are combined about 15MB while .skp file of a tree is 63MB. When tested, indigo also starts fairly faster with external meshes than with original model and dummy.

Hope other SketchUp users find this useful

Cheers!

Hello again, I just succeeded to make external mesh but there is no textures in the render, How can the textures appear correctly using external mesh? ... Thanks

[Yiqin]

@ Alamy:

This is a good tutorial, He (from mind.sight.studios) starts with Proxy mesh then does an example for an external mesh:

https://www.youtube.com/watch?v=nYhng66TEW4

In short though you need to have the materials IN your sketchup file and the names need to match the names referenced in the external mesh.

Good luck.