PDA

View Full Version : mimap question


royter
06-02-2009, 10:13 PM
i understand the importance of mimap filtering in CG, it tends to do what our eyes would do in a real world.
But why does the pixels of the texture shift a bit ( 1 pixel in u and v) with mimaping?
comparison (http://sor.typepad.com/files/shiftingpixelsmimaping.rar)
And why does mimaping (even eliptical mimaping) blurs the texture when the camera is close to the texture?
(it shouldn't because the level 0 of the mimap pyramid is used here and level 0 of the pyramid is exactly like the original image)

blazelet
06-06-2009, 08:50 PM
My understanding of mipmapping is that it pre filters all the images so that the renderer doesn't have to do any filtering. In this sense, even your level 0 would be like the original, but filtered ...

The -p flag creates a filtered pyramid image according to the /?

I don't know if any of that helps :)

royter
06-06-2009, 10:47 PM
My understanding of mipmapping is that it pre filters all the images so that the renderer doesn't have to do any filtering. In this sense, even your level 0 would be like the original, but filtered ...

it just doesn't make a lot of sense to me because mimaping is suppose to filter the smaller versions of the images in the pyramid as for the level 0,it does not need filtering


The -p flag creates a filtered pyramid image according to the /?


does this mean that if i am using the .map format (with -r -p), i don't need to turn ON "mimap" in the image file node?

Undseth
06-06-2009, 11:39 PM
Btw, I vaguely recall someone mentioning some time ago, that there is a gamma issue (linear/nonlinearissue) when using .map textues and the pyramid flag. Something about how a linear or nonlineared texture supposedly doesn't keep its gamma value through the pyramid layers.

I think it was maybe that Ctrl studio guy who mentioned it.

CGTalk Moderation
06-06-2009, 11:39 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.