Iray issue with Predatron Step Van (Taco Truck) - FIXED

CrissieB

I bought Predatron's Step Van Bundle to get the Taco Truck model, so I could change the textures and to make a coffee truck. I've changed the required textures, and my coffee truck looks pretty good ... except for a black area on the truck body, beneath the wing mirrors on each side (see first two attached renders). The black area also appears with the original textures (see third attached render).

Does anyone know what that black area is, and how to make it go away? Is there any contact info for the artist, so I can contact him for help?

Thanks,

Crissie Brown

 

Artbyphil

I havent got this but the only time I have seen something like this is when there are reversed normals. Not sure if it is that but could try selecting them with the geometry tool, and flipping them to see if it is that.

CrissieB

Thanks for your reply,

Had those normals been reversed, I would have seen the problem in Substance Painter when I was doing the textures. (SP does not display the 'back' of a surface.) Regardless, I tried flipping the normals on those polys, and it didn't solve the problem. So it's something else....

Artbyphil

strange cant think what that is then.

 

NorthOf45

Works okay for me. Can you use some of the other material settings? That particular area is part of the "20_Signs" material zone, which overlaps with the "14_MainBody" zone. If you have contrasting materials, you can see a bit of an interference pattern in the preview, which usually indicates more than one material occupying the same space (how it decides which to show on top, I don't know, they seem to be using the same mesh, or different meshes in the same place). However, the Signs material zone also covers most of the truck's sides and half of the side doors, and those don't seem to cause you problems. Have those reluctant polys been included in the surface group? I am quickly getting out my depth here...

CrissieB

Hi NorthOf45,

I tried the other truck presets and had the same problem.

Are you viewing/rendering in Iray? Those polys look fine when viewed in the standard Texture mode, and they render fine in 3Delight.

This happens when viewing/rendering in Iray, and it happens regardless of whether I've converted the materials with Iray Uber Base.

Crissie

NorthOf45

It looks okay in texture-shaded or Iray preview mode, 3DL or Iray renders, original materials or converted to Iray. Loading the Taco Truck, or applying the Taco Truck materials to another makes no difference. Is it the same on both sides? Looking at the maps for the signs, that area is masked out by the opacity map, and the main body doesn't have a mask. Try sliding the opacity level to zero and back on the 20_Signs and 14_MainBody surfaces to see if that gives a clue. There is a bump map on the main body, maybe try zeroing that out to see if it makes a difference.

CrissieB

Hi NorthOf45,

Hrmm. I zeroed the opacity on 20_Signs, but that didn't change the problem. And when I move the truck around in the scene, I get the problem in more areas (see attached render). Maybe I need to use the Geometry Editor to select the 20_Signs polys and simply delete them? That would fix the problem for my coffee truck, as I painted the signage directly on the truck surfaces. It wouldn't solve the problem if I decide to use any of the original truck presets, though, and I get the problem with all of them.

Crissie

NorthOf45

The bottom half of the door and the area under the poster are also in the Signs group. Removing it might take care of your coffee truck, but doesn't cure the root cause. I am at a loss, but I am no expert. Maybe someone else can jump in with their experience with this item...

CrissieB

FIXED!

As NorthOf45 suggested, the issue was that two sets of polys (the truck body and the signage) were in the same place. Iray didn't know which to render and, depending on the angle, simply didn't render either. I had this issue with all of the original models/materials, as well as my coffee truck.

To solve the problem, you need to modify the geometry of the truck base model. I used Blender, but you can do it with any modeling software. Here are the steps:

1. By default, the truck model is global Scale 92%. Change that to 100%. Hide any parented bits that adapt the truck for a particular vehicle -- Top Box, Panel, Satellite Dish, etc. -- and File>Export as model_name.obj (Wavefront Obj format). Note: DAZ's unit scale is 1cm and Blender's unit scale is 1m, so I export from DAZ at Scale 1%. Alternatively, you can export from DAZ at 100% and then rescale by 0.01 in Blender.
2. In Blender, import model_name.obj (click 'Keep Vertex Order' and check 'Poly Groups') and save the file as model_name_fix. Select the model_name figure, [tab] into Edit Mode, and deselect all polys. Go to the Textures panel, scroll down to 20_Signs, and Select to select all of the signs polys. Use [Alt-S] to move all of them along their normals by -0.002 (outward by 2mm). [tab] back to Object Mode and save the file, then File>Export>Wavefront.obj as model_name_fix.obj (see note below).
3. In DAZ, select the truck model, then Edit>Figure>Geometry>Update Base Geometry (Update Vertex Positions) with model_name_fix.obj. Reset the truck global Scale to 92%.

The 20_Signs polys and truck body polys no longer occupy the same space, so the truck will now render fine in Iray (see attached render).

Note: When importing an obj file from DAZ into Blender, always click 'Keep Vertex Order' and tick the 'Poly Groups' check box. When exporting an obj file from Blender for DAZ, always tick the Selection Only, Apply Modifiers, Include Edges, Write Normals, Include UVs, Write Materials, Polygroups, Objects as OBJ Objects, and Keep Vertex Order check boxes. I have these selections saved in Blender as DAZ defaults.

I haven't attached the fix.obj file because it's not my model to share. But it's very easy to fix.

Thanks to all for your help!

 

NorthOf45

Wow, that's dedication. In retrospect, I'm thinking maybe some kind of displacement map on the signs would do the same...?

Richard Haseltine

You could also use a Push Modifier in DS, apply a weight map, select by Surface to get the signs, and fill that section with a weight of 100%.

CrissieB

Hi NorthOf45 and Richard,

A displacement map on the 20_Signs material zone might do the same.

A Push Mod would also work, although I don't know how to apply a weight map to a Push Mod. 

Regardless, the fix was to get the 20_Signs polys out from the truck body polys.

Thank you all!

Crissie

Richard Haseltine

CrissieB said:

A Push Mod would also work, although I don't know how to apply a weight map to a Push Mod. 

1. Edit>Object>Geometry>Add Push Modiifer
2. Create>New Push Modifier Weight Node
3. Tools>Node Weight Map Brush
4. Window>Panes(Tabs)>Tool Settings
5. You should see the Unused Maps button listing the naem of your Push Modifier - click Add Map
6. right-click in Viewport>Geoemtry Selection>Select All
7. right-click in Viewport>Weight Editing>Fill Selected, enter a value of 0
8. right-click in Viewport>Geoemtry Selection>Select By>Surfaces>the panel's name (assumign it has one - if not you may to use one of the other selection options)
9. right-click in Viewport>Weight Editing>Fill Selected, enter a value of 1

Now the push modifer should affect only the sign, and you can adjust the offset in the Parameters pane as needed. This shoudl probably use less memory than a displacement map, and won't use any GPU memory as - unlike a displacement map - it's applied before the render.

CrissieB

Wow, Richard ... thank you for that step-by-step!

Crissie