Ambient Occusion Pass from Sketchup

[jlstorr]

Hello!

 

I'm trying to get an ambient occlusion pass from Sketchup (With Maxwell). The goal is to use exclusively Maxwell, and not rely on Maxwell Studio. I know how to create it from 3DS, but am having trouble getting it to work in sketchup. Specifically I can't find a shadows parameter when creating a material. Does anyone know a process that works?

 

Thanks!

[Brodie Geers]

Use material override to replace all your materials with a single material. Make sure that material has it's Shadow box checked

 

http://support.nextlimit.com/display/maxwelldocs/Shadow+channel

 

Run a render with the Shadow channel checked and use MultiLight. That should give you a different shadow channel for each light you have which you can composite in PS. If you use Skydome for your environment that will give you one shadow channel with a nice even ambient occlusion feel to it. There isn't much you can do to tweak it w/in Maxwell but you can bring it into PS and do a curves adjustment to affect the 'falloff' somewhat.

 

Let me know if that's not totally clear. I didn't do much to explain the particulars but if you're familiar with Maxwell hopefully that will mostly make sense.

 

-Brodie

[jlstorr]

Brodie,

 

I totally follow you. This is how I would do it from 3DS Max. The problem I'm getting is that it's not working for Sketchup. I'm using my "shadow" material that I created in Max, and linking it in Sketchup. The preview doesn't work, and when it renders, it renders with an empty shadow channel. I'll do a bit of research on Sketchup materials, that seems to be where the issue is coming in. Any thoughts would help.

 

Thanks!

[Brodie Geers]

so you've got a sketchup material that's linked to your .mxm? Perhaps you can post some screenshots of your mxm settings. Alternatively, you could export to Maxwell Studio and check out the settings there. Sometimes it's easier to find out what's going on from Studio and then you can go back and fix it in SU.

 

-Brodie

[jlstorr]

so you've got a sketchup material that's linked to your .mxm? Perhaps you can post some screenshots of your mxm settings. Alternatively, you could export to Maxwell Studio and check out the settings there. Sometimes it's easier to find out what's going on from Studio and then you can go back and fix it in SU.

 

-Brodie

 

I initially tried to get it to work with a Sketchup Material, but there wasn't a shadow option (at least not that I could find). So I used the Maxwell material Editor to make a material like I would in 3DS Max (like in the above article) and "linked" it in Sketchup. Sketchup seems to have an issue with materials that I've edited though....it reads the generic materials fine, but I'd I change a setting and save it, the preview goes away. It has to be something I'm doing...maybe saving it in a wrong location or something.

 

I personally trend away from Sketchup, but it's nice to be "quick" sometimes....not to mention comparability with the rest of the office. I'll try to take some screens tomorrow and run them by you if I'm still having issues.

[Brodie Geers]

I initially tried to get it to work with a Sketchup Material, but there wasn't a shadow option (at least not that I could find). So I used the Maxwell material Editor to make a material like I would in 3DS Max (like in the above article) and "linked" it in Sketchup. Sketchup seems to have an issue with materials that I've edited though....it reads the generic materials fine, but I'd I change a setting and save it, the preview goes away. It has to be something I'm doing...maybe saving it in a wrong location or something.

 

I personally trend away from Sketchup, but it's nice to be "quick" sometimes....not to mention comparability with the rest of the office. I'll try to take some screens tomorrow and run them by you if I'm still having issues.

 

I use both but prefer SketchUp. Sounds like you're linking materials correctly. Maybe some SketchUp screenshots.

[jlstorr]

Ok, now I'm lost...I'll try to take snapshots tonight, but here's the process I'm taking.

 

1. Create a box in Sketchup

2. Export to Maxwell Studio

3. Create a new Material. Use Wizard, make it plastic

4. Click on "Material Properties" and check Shadow

5. Go to "Channels" and select Shadow

6. Render

7. Select the Shadow Channel...it's empty, just white

 

 

Am I missing a step? Do I need to toggle something else?

 

Thanks!

[Brodie Geers]

Sounds like you're doing it correctly but perhaps misunderstanding what the shadow channel does. When you check the Shadow box for a material it tells Maxwell that that material should receive and show shadows. The idea is that you can check the Shadow box on a grass plane material, then you'll have an image that's all white except where there's grass you'll see the shadows. When you replace the grass plane in photoshop you can then overlay the shadow channel and set it to multiply to get your shadows back.

 

So with your example there's nothing casting shadows on the box so it's all white. If you place the box on a plane with the same material you should see a bit of shading where the box meets the plane. Or if you use the sun as an environment you should see the dark side of the box as well as the shadow cast onto the plane.

 

-Brodie

[jlstorr]

Ok, I figured it out (kind of), here's what was happening.

 

Disclaimer: I'm not sure why my initial test didn't work. I hear what you're saying about just a box, but it should have had some slight shadows on the edge from the light IMO. I tweaked the sun in Sketchup, but no no avail. Changed to Physical sky, nothing. Discarded the scene and started over.

 

1. I created a scene (again) in Sketchup, consisting of a floor plane, and a few boxes with randomly extruded faces. I applied two separate materials, linked them to the .mxm file (with shadows checked) and exported it to studio.

2. Queued the render up, and checked the shadow channel....it was empty.

3. Went back to studio, clicked on the individual textures and reloaded the material. Rendered it out...bam, it worked.

4. Went back to Sketchup, did a render with the shadow channel selected linked to the .mxm that worked in Studio......didn't work.

 

 

So at this point, I can create a model in Sketchup, export it to Studio and re-link the materials manually to get the desired effect. Not sure why it's not working from sketchup natively, but I've had issues working with .mxm materials in sketchup to begin with. I can create a sketchup material and make it a generic emitter for instance, but when I link it to a .mxm material the scene doesn't see it, and it breaks. Often times when I link a Sketchup material to a .mxm material and try to edit it from sketchup (as in it opens the maxwell material editor) sketchup will freeze and crash.

 

I'll keep digging on this. Would be nice to do it directly from sketchup, but thanks for your help Brodie!

[Brodie Geers]

Hrm...sounds like an odd bug somewhere. Where are your mxm's that you're linking to? Just on your C drive or networked somewhere? I think there's an option in there somewhere to save out your materials when you export - like Maxwell's pack n go feature. Maybe turn that off? Maybe even try uninstalling and reinstalling the plugin. Sounds like you're doing it right just running into a bug I haven't heard of. You may think about emailing JD, the plugin's creator. PM me if you'd like his email.

 

-Brodie