How do I get single sided objects in the ART renderer?

[Anonymous]

How do I get the ART Render to ignore the back face of my object in render? I've searched all over and haven't found much, maybe I'm not looking in the right places. See my two very simple setups: brand new scene, add a box, flip the front face and a plane. No materials applied. Everything else is default.

See the screenshots: a scanline render doesn't render the back sides of the faces, but the ART renderer does. What can I do to get the ART renderer to ignore the back faces? Thanks in advance.

[Francisco_Penaloza]

You could do something that will work half of the way, You can apply a matte shadow shader to the geometry and set the color to pure white, this will make the back faces invisible, but the object will still cast shadows. The problem is Art render is a basic functionality render engine, it is quick to use but it doesn't have many features.

There is no development on it either so I would recommend trying a different render engine if you don't want or can use Scaline.

Arnold could do the trick in this case, you can create a double side shader with a matte shader for the back.

Other render engines such as V-Ray or Coronal also could do the same.

[Anonymous]

No reason I can't use Arnold. I'm attempting to convert a model that was built a long time ago (like 2005-ish) and used mental ray to render. So I am new fairly new to ART and Arnold, so it's going to be a learning process. 

Here's a screenshot of one of the files I'm trying to convert, I applied a two-sided material with matte (materials->arnold->surface->matte) as the back. But the windows are just black. There are a bunch of buildings and windows in this file, I'm really not excited about going through and deleting the back face for each window in each building, but I'm thinking that's my next step.

[madsd]

Use Arnold, especially if we talk Architecture & vegetation and any other larger project.
Arnold 2 sided material, the backfaces has opacity set to 0,0,0

[Anonymous]

Yes! That's exactly what I'm looking for ... why doesn't mine do that? What am I missing?

[madsd]

I dont know, you didnt upload any scene data to poke on.

Attached my basic scene. Try see if that improves things.

downsaved from most recent max version to 2018

Remember to grab the latest build, they just pushed a new one yesterday.

https://www.arnoldrenderer.com/arnold/download/#3dsmax

[Francisco_Penaloza]

To add what @madsd  posted, be sure that the normal orientation of your faces is the way you need them, maybe your windows normals are pointing in the wrong direction.

Now, why you do need to 'hide' the back faces of that building windows?? remember with Raytracing anything that gets occluded by other object or shader won't be calculated. in your case, you won't render the interior wall of that building, unless of course, they are visible through a window.

Now for the glass, you'll get a better result if your glass panel is built as in real life, so 4 faces, front back top, and bottom.

IF that file is from 2005 all those 'old trick of single face windows or hide here and there, all those tricks are not relevant anymore, just build as real life, up to scale and you'll get the best results.

[Anonymous]

I think I'm getting somewhere -- it appears that this works only when one or two of the faces of the box are flipped (right), but in the case of these models, all of the faces on the box are flipped and it makes everything black (left). 

I attached my test file if you have any desire to play around with it, but I think I'm just going to have to go through and manually fix everything. Thanks for all of your help, I appreciate it.

[madsd · Accepted solution]

Try see if this improves the situation.

Add and Arnold Properties modifier to the mesh and tick flip normals.

As for the front and back conditions, I just set it so it matched the right one.

You can select a bunch of objects and instance the setting from the Arnold Properties modifier.

Also, most important aspect actually:

Note I set the render engine to Active shade, so its rendering live.
This will speed up your experience tremendously, as when you work with a problem, the render frame buffer updates instantly as you tick some feature, or pull a spinner. So superior to the production mode I got with the file.

[Anonymous · Accepted solution]

Unfortunately, selecting the front face of the box and flipping it doesn't really do much for me - it looks like that was one of the steps here. Since the box with all faces flipped is just one of many window containers on one building, which is one of many buildings in the entire model and each boxes around the windows aren't instances of each other, that still leaves me with needing to go through and select each window and do something to it. That is what I'm trying to avoid, and in that case, it's probably best to just delete the front face anyway since it's not really supposed to be there. But I think that's what I'm faced with.

Thanks for your help looking into this. I definitely appreciate it. I love the active shade engine.

[madsd]

Can you try delete whole scene, except a couple of windows untouched?

Preferably some windows sitting in different viewing angles.
So a south facing window and an east facing window.

We can perhaps use an analytic normal to filter the face out, as the windows will point in some direction we can use that info, shade space to isolate, or include.

[Francisco_Penaloza]

SO why you need to hide the back faces any ways??

[Anonymous]

Here's one of the buildings with only the windows and the boxes if you want to play around with it. 

But I have moved on ... it's a mindless repetitive task, but I'm a window container deleting machine 🙂