Decal distortion

[Aleta]

I wanted to interact some 3D animation with an image, to make an interesting DVD menu. I'm a new user, and found that decals seemed to be my best option.

 

So, while using "snap to grid" I modelled a perfect box, and applied my decal on it. It looked perfect. Until I rendered it. Then there was distortion. The distortion is mainly visible in the upper left quadrant, and may be present only there. And it is _very_ visible.

 

Once in a hundred tries I did not see the distortion, but I didn't do anything different at that lucky shot. I'm even beginning to doubt that it even happened... Is it a bug, or is it me?

 

I'm using A:M v8.5 with Windows XP pro on a pretty powerfull PC, (and A:M crashes constantly by the way. But if that is an upgrade issue, I won't have time to remedy that before the DVD must be finished).

[Eric2575]

In situations where you are talking about specific, repeatable visual distortions, it's always a good idea to post a rendering of the issue and a wireframe of the affected area. It's hard to diagnose with a written description only.

[JohnArtbox]

Are you using the latest version of 8.5? if not you can download it from ftp.hash.com/pub/updates. 8.5 was one of the most stable AM versions by the end of its evolution.

For something like this an image and a wireframe make it easier to understand.(Edit:Damn, Eric beat me to it )

For example if the cube has one patch on each side,then you may have more luck with a cube with 4 patches a side.

Or try the planar projection map and see if that produces the same problem. If not use that.

Good luck

[Paul Forwood]

It's a little difficult remembering back to 8.5 but I would guess that you have some internal patches. You might have accidentally extruded some geometry that is sitting in the same space as the original geometry and slightly 'popping' in the corner where you are getting the distortion.

 

This is only guess work though so maybe you should just make a new box and try it again. If you copy this cube to a new object you can right click in the object window and select 'Info' to give you the total number of patches. That should give you a clue as to whether there is extra geometry in there. Or you could just click on a spline, rather than a cp, and nudge the highlighted cp using the cursor keys. This will also expose any extra geometry.

 

Maybe Dearmad will see this and offer advice. He has been making his movie with this version so may be able to shed some light.

 

Good luck with solving this

[Aleta]

Thank you, everybody!

 

I downloaded the 8.5+ and 8.5++ upgrades, but that made no difference.

 

This is my box. Very simple, and the middle patchwork is made to mimic the simplest kind in the manual.

 

 

[attachmentid=15028]

 

 

And then the distortion:

 

 

[attachmentid=15031]

 

 

Which interestingly enough was no distortion at my first attempt of catching it:

 

 

[attachmentid=15030]

 

 

There might be a clue hidden here, though. The undistorted image was captured in Low res mode, whereas the distorted ones are in PAL D1 (or TGA) resolution.

[Paul Forwood]

Three-point patches have caused problems with distortion in the past as I recall. If this is the dominant image on your object why not make the dominant face of your cube with a four-point patch, or even 4 four-point patches? It could help.

[Aleta]

Three-point patches have caused problems with distortion in the past as I recall. If this is the dominant image on your object why not make the dominant face of your cube with a four-point patch, or even 4 four-point patches? It could help.

 

 

 

I'm sorry, but I'm such a newbie that I don't understand your advice.

[Paul Forwood]

Don't worry, Aleta, it's an ongoing battle for all of us. ;-)

 

I will try to make it a bit clearer:

 

At the moment it looks like you have this decal applied to one of the sides of your cube that is made from four triangular patches. If that is the case try making a new cube that does not use these triangular patches or adjust your current cube so that the bigger sides are made from four-point patches. Apply your decal to the four point patches and see if it still distorts.

 

Three point patches are better at handling decals now but I seem to remember that there were issues in earlier versions of A:M.

 

Edit: Actually they can still be a problem in later versions, as I have just experienced myself! Best to avoid 3 and 5 point patches where possible or try to limit them to areas that are not so prominant.

 

Is that any clearer? I hope so :-)

[Aleta]

Well, the four-patch-approach seems to have done the trick! Thank you very much!