see attached image.. this is with the default texture. the same happens on the rolled tarp. also happens with no texture at all. if rendered with poser 5 engine, the pictured occurs. poser 4 engine has much smaller black artifacts, but they are still there. happens even when I change material completely (i.e. to gold). tried reinstalling the chuckwagon, no change. odd fact: if I load the .obj of the tarp in bryce, I can see random triangles in the wireframe preview which seem to match up with the ones pictured.. however if the object is rendered in bryce, no visible artifacts. tried messing with the texture mapping settings, no change. without wagon, the artifacts appear brown instead of black. any ideas? no issues with any other probs, the wagon itself, or any other item, only the tarp.

Poser uses a radically different scale factor to other 3D programs, and also expects polygons to have only one side. The first is why objects imported from other 3D software can look incredibly big. Also, if am object is made in some other program, in a Poser-suitable size, there can be a loss of precision. So suddenly the inside surface of the tarp, black because it is unlit, shows on the outside. And because Poser only expects polygons to have a single side, Poser will default to rendering polygons seen from the wrong side. That way, you avoid embarrassing holes where the view shows the inside of a sleeve cuff. There's an option in rendering whether or not to render back-facing polygons, and this might cure your problem.

A little displacement usually fixes the problem. Here is how to set it up on whatever material is having difficulty. The Displacement value usually needs to be higher than 0.001 shown here, but try this first, then increase the value by small amounts to find the point where it works best. As I recall on the tarp it worked well at about 0.05, but you can go up to 0.1 on most things without altering the shape too much.

Actually, the option to not render back facing polygons won't work. I remember seeing a technical explanation somewhere in the forums about this...

IIRC, the problem here is that Poser's engine, due to lack of precision, can't decide which polygon should be the back-facing polygon. So it renders two polygons in the same 3D space with apparently the same normal facing.

A polygon whose normals are facing completely away from the camera shouldn't render black. It shouldn't render at all regardless of whether or not it receives light.

One solution I've found to work here is to apply a displacement map to the tarp. The displacement map doesn't have to be an actual image. In the Materials Room, using a Math Node with a Simple Colour sub-node set to plain white seems to work.

You'll have to play around displacement value and ramp it up gradually until the black parts disappear.

Message edited on: 11/27/2004 08:10

Thanks for the reminders. There's likely several ways of getting that input to the displacement node. I've just had the same problem with a window in a wall-prop, and used the default math function. (Also, as has been recommened in another thread, used the background picture as a texture-input to the Ambient channel on a square prop.)

using the displacement map worked fine.. thanks a lot for the tips.