Hello there! I don't know if any of you has ever encountered this problem but it has troubled me several times until now. I couldn't find any messages in the archive conserning it. Still I'm going to tell you the solution hoping that it helps at least someone since I've faced it so many times. I've discovered that images that have large black areas create flaws on the surface when used in the bumpchannel. As you you can see in the face of the clock is filled with black artefacts while it should be clear and white with only the numbers and the name of the creator raised and black. The problem was fixed by changing the value of the black in the image (to be used as a bumpmap) in Photoshop(or whatever you use) from 0 to 1 i.e. red, green and blue all to 1. -Hannu Kulju

I have never heard it! If I ever run into this problem I know what to do. You could try what happens if you use a greyscale image (so no red, green and blue, but just one greychannel), I wonder if it shows up then.

Yep, it does the trick and the flaws disappear. I'll use grayscale images from now on for they are a bit smaller too. Thanks. I tried to recreate the problem with a simpler model with less facets and it didn't happen so maybe it has something to do with file complexity. The file the problem occurs in has over 250k facets and 500 objects. As you can see from the picture there are a few objects in the scene and there are more details inside the cuckoo clock on the back wall. This is a scene of an animation where camera shoots first at the clock then glances around the room and finally flies in through the door of the clock viewing the inside of the clock. -Hannu Kulju

Well I'll be danged! I think you should tell Eovia about this as well. Thanks for the post and the fix! This is a new one for me. -Kix

HK, I believe you were using a JPG image as the bump map? This I'm assuming this from the fact that those lines look like compression artifacts that you get from JPG images. If I'm wrong, OOPS... But Hoof has it right... use a greyscale image in either bmp or tif format... this is lossless and will result in nice clean lines... usually. Ken

Ken beat me to it. I was going to suggest that the problem might have been from jpeg compression. That also causes lots of problems with transparency maps.... Usually you can get away with jpegs for color maps, but transparency and bump need very clear files.

I recall when trying a Poser figure out in Carrara window I needed to add a Shader Ops function to make the black of a JPEG'd transmap truly black. So when a color image is used as a bumpmap, do you get more levels of height, or does it bump it down to the same numbers as a greyscale?

Yeah, it would be safer to use a tiff image for the bumpmap. But when you desaturate a color image in APS to get a bump map, Carrara probably performs the same function (desaturation), so it would "bump down" the same.

nomuse, I believe that the bump algorithm reads the luminence value and uses that as the key, so no, you wouldn't get any more levels of height. This is not true of HDRI though, and you can get an awful lot more levels of light using the HDR format than standard LDR (BMP,JPG, TIF)... [sorry for the OT non-sequiter, still working on the tuto for creating your own HDR's: It's tough making sure that you can duplicate your own work!]. Ken

So HRDI might be the key to that old "stair-step" problem, eh? Hope this isn't TOO far off topic! :>

Nope, sorry nomuse. HDR is strictly a lighting format. Used for creating lightdome lighting from images and imagemaps. The lighting that you can get from them is quite superb, but that is a topic for another day... or at least until I finish the tutorial... Here's a sample of what I've done with some of the tutorial stuff... no lights, just the HDR image in the background setting. The HDR image is of a Christmas tree picture from 2 years ago.... Ken 

If anyone still remembers the original topic... :)

This morning I reopened the C-file and the flaws were back even with the grayscale image. For those who thought it was the jpg-format that caused the errors, I must unfortunately tell that the original file was tif that was saved from psd and this morning I saved a grayscale tif file from the original psd again. The problem still occurs, not when I set the texture file but when I reopen Carrara and the file with the texture.

So, grayscaling the image may have not been the answer after all. What strikes me wierd is that if the jpg image has errors on its black areas, shouldn't the errors repeat when I just change the minimum value of colours from 0 to 1 and save the image. I did the value change by altering the output range in Photoshop's Levels-window.

It might be a mac related problem too, so those of you who use PCs know nothing of it. I don't know how much differences are the between mac and PC version. With bugs I mean, the programs should be the same.

• Hannu Kulju

HK, Could you send me a copy of the file that you used in C3? The TIF would be fine. I want to check it out and see if this does the same thing in my machine (a PC). If necessary I can report the bug to Eovia if it is cross platform, or even if it isn't. Ken

cckens, I'm afraid the filesize is about 19 megs. Which in fact might be one reason for the errors. As I exported just the one object that had the flaws, the flaws disappeared. I also started to think that the face of the clock is a part of a larger vertex object that has about 10 shading domains. It might be easier for the program if the shading domains were separate objects. I'm beginning to feel that this is something that has occurred when the computer has crashed while I've been working with the C-file. Computers tend to do it when I'm around.

Your black and white TIFF image is 19 MB? That's ridiculous. What possible reason could you have for making it so big?

I would think that sticking this image on a simple plane would be a good place to start troubleshooting. Simple minded but easy!

It would certainly explain a lot but no. I do like to have my textures sharp but not that sharp. The Carrara file is 19 megs. I understood that cckens would have liked to have both the C-file and the tiff-file so that he could test if the problem occurred also on PC. So, I tried to make the C-file's size a bit smaller by exporting just the object that has the errors. I closed the original file and opened the file with the exported object and rendered. The flaws were gone, even with the original tiff-file. Of course I can send anyone the original tiff-file but it is probably no use. The problem derives either from the C-file's size or something else that is in the file for also the curtains and the walls have been filled with similar errors.

Why don't you just blur and decrease contrast of your image ? Carrara just don't like such sharp image for bump. J-R