greyscale texture map in transparency channel

[Jack 3D]

Hi. Thanks for all the replies to my previous posts from a few months ago. I'm importing a b & w high quality 300 dpi jpeg as a texture map into the transparency channel of a newly created shader. The image is some black type on a white background. In the shader panel I've checked off No Light Interactions When Fully Transparent and in the Render panel I've checked off Light through Trans. I'm using the shader on a sphere which has a slightly smaller inner sphere centered within it. The inner sphere has a simple shader applied to it. Only the type is visible on the outer sphere which gives the effect of a line of characters mapped to an invisible spherical surface rotating (if animated) around a globe and casting shadows on the surface of the globe. The problem is that the edges of the letters are not perfectly clean and there are some visible artifacts around them. I'm using what I think are the highest render settings and have even tried importing the image at a higher resolution but still there are these bits of artifacts which show up as ragged auras. Is there any way to get perfectly clean edges on the black and white image I am importing as a texture map? Thanks for any replies. Jack 3D

[medeamajic]

Make sure you do not use anti aliasing for a clean look. I admit It could be something else. I am having troubles it the bump channel. I do not know if the image file matters (JPEG TIFF BMP).

[rickei]

For this effect you will need to put you texture map in the ALPHA chanel.

[Jack 3D]

Thanks for the replies. I found that w/ anti-aliasing unchecked the edges were noticeable ragged. They were better at the Best setting. What seems to be working is saving the black & white image for import at a very high resolution (1200 dpi) and bringing that into the transparency channel of the Carrara shader. The final render looks pretty good. I would like to understand better how to bring the texture map into the alpha channel as was also suggested. Do you mean export the greyscale image that is to be used as a texture map at a 32 bit depth including the alpha channel? I tried that and it didn't make any difference. Or do you mean something else?

[dbigers]

You might also try the interpolation setting for the texture. Generally that setting is most noticable when you are rendering at a higher resolution than the original, but I have noticed it to help in other situations as well. Good luck.

[rickei]

Apply your existing greyscale map in the Alpha chanel of the Carrara shader tree

[medeamajic]

When you make the grey scale image in Photoshop and save it with antialiasing sometimes it does not look crisp and clean.