Rendering "just what we see"

Second Technician Rimmer

Is it possible to make DS render only what is seen in the viewport? For example, if I load a landscape including a serious chunk of cliff/cave that is one single mesh, it is my (wrong?) understanding that the engine will be working not just on what is in my camera's field of view. Must I resort to stripping the mesh from some parts in Blender? Somehow it feels a bit overkill... the idea here is to keep just that visible part of the environment and its props to be rendered. Hiding elements in the SCENE tab isn't going to help since it'd hide the whole cliff.

Richard Haseltine

You could try a cliping plane to hide soem of the mesh,or you could use the Geometry Editor to do a quick marquee select/assign to selection set/hide. However, bear in mnd that even things which are out of the line-of-sight can still appear in reflections, and can still influence the lighting by blocking or bouncing.

Second Technician Rimmer

My purpose here is to find a trick to reduce the amount of polys my system will have to render while retaining the section of decor I intend to show on the final render. I tried the clipping plane. It didn't really help but it's a neat trick nonetheless that I will use in the future for easier camera placement.

I tried the Geom editor too. I went as far as not just hiding but editing out parts of the mesh. And I mean, *huge* parts! However, the amount of Vram remlains consistent with what it was when I loaded the scene "as is". If there are less polys, shouldn't there be an improvement?

Richard Haseltine

Yes, deleting polygons (or simply hiding mesh) certainly should cut memory use. However, do bear in mind that the major consumer of RAM in most scenes will not be the mesh but the textures.

Second Technician Rimmer

Alright. I managed to break down a procedure, based on your suggestion regarding textures, Richard, and I am very glad I listened to you :D. 

If some noobs such as me need to ease the stress put on their rig as they try to render a demanding scene, here is what I did. I had to include an external link so I hope it's okay, since it's a non-commercial item.

BEWARE: before you start to do this, save your "heavy" scene. You will need to come back here later on. It's very important.

1- Grab and include in your library the script kindly provided by Esemwy in this thread as well as mccasual's excellent mcAltTex script. His scripts page has many items so to find it search for "switch all textures" in the page. Thoese two scripts are going to become your very good friends.

2- Load your scene.

3- Select the elements in the Scene tab. In the Surfaces tab, Editor section, select the surfaces.

4- Apply the script.

Careful now: the script has indeed created a bunch of reduced (by half) textures, however, they are stored in a temporary folder. Before going any further, you'll want to copy those. 

5- Open your DS temporary folder. The coveted textures will be there. Select them all, copy  and paste them in a folder where you will want them to stay for future use. What I do is creating that folder in the same place where the folder for the original textures are and use the same folder name with LORES at the end.

6- Now you'll have to do some renaming. These textures have the original names plus a _SIZEVALUExSIZEVALUE before the .extension bit. Remove that values section in every file name.

7- reload the original scene with the "large" textures.

8- It's now time to use mcCasual's script and direct it to your xxxLORES folder. This will replace all the texture in the "heavy" scene with the lower resolution version.

9- Save that scene as new. Maybe once again name it the same as the heavy scene, with a LORES suffix for disambiguation.

10- Profit.

Now of course, there are a few things to remember. When it's about a decor, this works very well. If you're going to add characters, think carefully. For example, if your characters are farther from the camera and especially if you are using deapth of field, you can create versions of your characters with a lower resolution set of thextures, just the same we did for the scene. A character in close-up or with depth of field centered on it will look way better with its original textures.