image filtering and texmap filtering are 2 COMPLETELY different things.
BTW: yes, bump mapping needs always some filtering to work, the algorithm is based on it.
so keymaster, for bitmaps in the bump slot one should always use filtering like pyramidal or summed area instead of none? and what about the blur values?
it was my impression with vray 2.0 that everything worked quite well with almost every map set to filter=none and blur 0,01 so we tried to apply that to corona as well. but as people like juraj stated, the matter is probably a bit more complicated.
the attached image was rendered with corona (only a little post color/contrast/glow) to illustrate a room of an old house we are planning/converting currently (architectural design not visualization mostly)
it´s not meant to be something special or a nice visualization on it´s own but just part of the planning process... anyway, the thing is, in this scene (because it had to cost no time) every single map was set to filtering=none and blur 0,01. even the bumpmaps... we rendered it in 3000px wide and with about 100 passes, turned out quite fine i think, no? i mean especially the (quite dramatic and not very well mapped) bump mapping looks like it works to me?
besides this filtering issues the scene uses every conceivable sin like color correct maps (they are supposed to be slow too?!) for single bitmaps to alter brightness and contrast for using them in different slots of the materials (diffuse, bump, reflection). plus it is lit via an HDR light outside and a few smaller visible and invisible spheres and planes inside... rendertimes for those 100 passes were not very high and i think to get the same out of the box result with vray in reasonable time we would have had a hard time.
so thanks, conclusion again, corona is awesome. just my 2 cents to the topic, not very scientific. ;)
we will experiment a bit more with this whole bitmap filtering stuff i guess, always a pleasure to read how other people do it.
best regards,
chris.