CompuServe Thread

#Brushmap Seams

4 messages in this thread
#3371From: Tim Wilson [Crestline]Jan 22, 1995 4:09 PM
Marc, I hope you won't mind me responding to your message to Mike in “Interace 3.2'', but I think a little clarification is in order. There are two different types of seams that occur on Altitude maps. And we're starting to get them a little confused. When wrapping any spherical or cylindrical map (whether it be color, filter, altitude, whatever…) there is a seam created where the opposite edges of the image meet when they wrap around. You can get the two borders of the image to match up properly, and eliminate this type of seam, by processing your image BEFORE you apply it to the object. The other type of seam,… the one we've been talking about, ONLY occurs with ALTITUDE maps; And causes a noticeable GREY LINE to appear where the edges of the Altitude maps meet. This apparently is part of the Altitude mapping procedure. But there is a work-around for this as well. It's a bit nasty, but perhaps it's worth reiterating here. >>To get rid of the `Altitude' seam on a flat surface with a REPEATED Altitude map, you can tile the maps together in an image processor BEFORE applying them, and not use the Repeat command at all. But this won't fix the `Altitude' seam on Cylindrical or Spherical maps. So here's a nasty work-around for that. Create a Front and Back Hemisphere for your object using Subgroups. Take the bump map into an image processor like ADPro, and ROLL the seam so its exactly in the middle of the image. Apply the original bump image to the Front Hemisphere Subgroup, apply the rolled image (with the Brush axis also rotated 180 degrees in Z) to the Back Hemisphere Subgroup. This way you hide the `Altitude' seams of both images in a part of the object where they aren't visible. Altitude maps apparently make a smooth transition across Subgroup boundaries. << Tim
#3373From: Marc ReinigJan 22, 1995 5:10 PM
Tim, >> I hope you won't mind me responding to your message to Mike … No, I don't mind at all. Any help or clarification is always appreciated. I just hope Mike understands that, while I know from a developers point of view it may be a design flaw, from a user's point of view, it is the same as a bug, ie. I think it should be fixed. In prioritizing it, I would put it below adding soft shadows (sorry, I just had to fit that in ;=) I'll be good, now.). In terms of the altitude map, if I understand what you are saying, on a flat surface you can't use Repeat, you tile it yourself. This sounds like an adequate work around in most cases, but if you zoom in could be a problem due to lost resolution. On a cylindrical or spherical surface you also can't use Repeat, instead you again create the tiled map but roll it, split the object into two subgroups and map separately onto each subgroup rotating appropriatly. >> This way you hide the `Altitude' seams of both images in a part of the object where they aren't visible. Altitude maps apparently make a smooth transition across Subgroup boundaries. << I'm not sure I understood this. Are the seams there? If I rotate around and look from the side will I see them? Or, are they not there because I would not be using Repeat? As long as it works, of course, that is the important thing, I just am trying to make sure I "understand." BTW, sorry about the shadows ;=) and I want you to know that I'll become a customer with my next contract as part of my policy of, "Always, reinvest at least 10% of your revenues in key new hardware and software." -Marco
#3377From: Tim Wilson [Crestline]Jan 22, 1995 6:22 PM
Marc, >>On a cylindrical or spherical surface you also can't use Repeat, instead you again create the tiled map but roll it, split the object into two subgroups and map separately onto each subgroup rotating appropriatly. << The Repeat setting does not work on Cylindrical (Flat X, Wrap Z) and Spherical (Wrap X, Wrap Z) mapping AT ALL, so forget about that. You don't have to do any tiling before you apply a map of this type. You just need to make another SEPARATE image map, with the seam `rolled' into the center of the image. >>This way you hide the `Altitude' seams of both images in a part of the object where they aren't visible.<< This was probably a poor way to put it. If you apply a Spherical or Cylindrical map exclusively to a Subgroup, only part of the image will show up on the rendered object. So the idea is to make sure the part that shows up on the Subgroup does not contain the `Altitude' seam. You do this by rotating the second map 180 degrees as I described. >>If I rotate around and look from the side will I see them?<< By using two images with seams in different places, applied to two opposite Subgroups, you can prevent either `Altitude' seam from being visible anywhere on the object. Tim P.S. Please remember that these remarks relate to the unique seam created ONLY by Altitude maps.
#3383From: Marc ReinigJan 22, 1995 9:21 PM
Tim, Thanks for the detailed and informative response. I'm off to try it. ;=) Marco