Send me the image with the alpha and I'll take a look.
JF
Same problem causes that i started with Grass/Fur generator... I needed grass...
Try this One and set it as to be parametric on surface....
Christiaan... uppload that yours for them, so they can find problem...
How did you apply it?... What are your settings of material?...
It looks to me like you have your alpha inverted and the part you are seeing is the opposite of what you want. The best way to do this is make sure you are using an RGB Alpha, don't try to chroma key using a JPEG it will always leave you with artifacts. I have attached a modified version of the file you sent me so give this a try.
The problem with the texture map overlapping at the top of the surface a co-worker is currently looking into. There is also a problem with opacity amount maps not working correctly which will be fixed in the next update.
There is a difference between using an opacity amount map and using a texture with alpha as a pattern map and switching On "Transparent Background". Using the transparent background toggle means that where the alpha is 100% the material doesnt exist. i.e. you wont get any refraction, dispersion surface properties displayed. Where as if you use an opacity amount map these properties still aplicable where the map is 100% transparent.
Regards
Paul Chater
I don't know if it is related but I have had this problem with other ray tracers (final render, for example) and the only way to make it work was to disable map resampling.
Regards.
Iván