So i got a model i want to bake a 4k AO texture to, but for some reason it doesnt work.... When i try to bake a smaller pixel texture + less rays it works all fine but as soon as i try with 1024 rays + 4092 pixel texture it all is just messing up for me ...

for example, if i bake ao with 512 pixels and about 128 rays i get a nice texture image, with the right name, and it creates a new lambert for me with the AO linked, this lambert is connected to the object. All good. But once i try to do the same process with 4k pixels instead of 512 and about 1k rays i get to wait about 3 hours and all i get is a black image/part of texture baked/no texture at all/an odd image file, it doesnt create a new lambert with the ao assigned to it etc. its just messing with me. i dont know how to create this high definition AO that im looking for ....

Im doing Batch bake (mental ray) btw.

any suggestions?

thanks - skalman