[LDCad] Model is too large for 3D rendering software

[kevlamar]

I have built a very large model which I currently have saved as Ldraw files.  This is a model consisting of over 157,000 pieces. I have attached a few still images to give you the sense of how large this model is.  The model is of a town I grew up in and my dream and end goal was to produce a video flyover that looks like a realistic lego model so I can share it on social media.  The problem is that coming in at 157,000 parts, it is just too large for 3D programs to handle and render 3D video. I have tried outsourcing the project to a skilled 3D artist and after a week of trying he admitted defeat and said even though he has a top-end system, the 157,000 pieces was too much.  He said the only solution he can think of is to combine many of the individual legos into solid pieces to reduce the complexity of the file. I don’t know if that is even possible.  I am currently opening the files with LeoCad which allows me to render them as 3DS or DAE file (however, since the model is so large I have to separate it in 4 sections to render it then put the sections back together after it is rendered)

If there is anyone out there that has advice, either combining legos or rendering enormous files into video via other routes I would be very grateful.  This project has been shelved for two years because this problem proven so difficult. I am willing to pay for professional services to make this happen.  If you would like me to upload the files just let me know.

[Matthew Morrison]

I have built a very large model which I currently have saved as Ldraw files.  This is a model consisting of over 157,000 pieces. I have attached a few still images to give you the sense of how large this model is.  The model is of a town I grew up in and my dream and end goal was to produce a video flyover that looks like a realistic lego model so I can share it on social media.  The problem is that coming in at 157,000 parts, it is just too large for 3D programs to handle and render 3D video. I have tried outsourcing the project to a skilled 3D artist and after a week of trying he admitted defeat and said even though he has a top-end system, the 157,000 pieces was too much.  He said the only solution he can think of is to combine many of the individual legos into solid pieces to reduce the complexity of the file. I don’t know if that is even possible.  I am currently opening the files with LeoCad which allows me to render them as 3DS or DAE file (however, since the model is so large I have to separate it in 4 sections to render it then put the sections back together after it is rendered)

If there is anyone out there that has advice, either combining legos or rendering enormous files into video via other routes I would be very grateful.  This project has been shelved for two years because this problem proven so difficult. I am willing to pay for professional services to make this happen.  If you would like me to upload the files just let me know.

The only way I can see this working is to split the project into several sub projects that are of a manageable size.

At that point you can open them individually in an already built viewer, or you can write a purpose built viewer that selectively loads only what's actually visible.

If you want to view the entire thing at once in a system like that, you'd have to put in some kind of LOD system that replaces the full resolution elements with low polygon analogues. It's what game engines do, so it's not a new problem and there's bound to be a ton of documentation on how to do such a thing.

I'm working towards implementing something like this in my blender plugin for datsville. As it stands, there's nothing that I know of that loads it either.

[Roland Melkert]

If you want to view the entire thing at once in a system like that, you'd have to put in some kind of LOD system that replaces the full resolution elements with low polygon analogues. It's what game engines do, so it's not a new problem and there's bound to be a ton of documentation on how to do such a thing.

LDCad currently only applies frustum culling to things behind the camera (so Z tests only).

And it disables rendering of edges for stuff at a certain distance.

The 2.0 engine was supposed to improve on this.

[Jonathan N]

The easiest option is probably to render it in a path tracer like Blender Cycles if you want it to look realistic. The problem with opening large LEGO models in realtime rendering programs like others mentioned is all the geometry. Doubling the amount of geometry means your graphics card has to do about double the work. Doubling the geometry in a ray tracer or path tracer like cycles only adds a little bit of extra work since it's not actually rendering the scene triangle by triangle. I would still expect a 3D viewport render to always be faster than a Cycles render. The rendered Cycles viewport in Blender can sometimes be more responsive than a traditional 3D viewport since it doesn't need to render out complete frames.

Cycles isn't the fastest renderer, so you may have better luck in Blender with something that runs in realtime like Eevee. It depends on what quality you want in terms of lighting and material accuracy.

You can try installing the latest version of Blender and importing the model using the new importer linked below. It should easily handle 150000 pieces if you enable the instance on faces option when importing. I've been able to import and render Datsville (400000+ pieces) without any issues. From my experience, large scenes import into Blender faster than opening in LDView, LeoCAD, etc. This is the first release, so there may be some issues like not being able to load some files. Please let me know if you run into any problems.
https://github.com/ScanMountGoat/ldr_tools_blender

[Willy Tschager]

He said the only solution he can think of is to combine many of the individual legos into solid pieces to reduce the complexity of the file.

You could give LDBoxer a try.

https://github.com/Jeremy1980/LDBoxer

w.