Skyboxes + Distortion

[Anonymous]

I've been through just about every tutorial I can find, downloaded every pre-made image there is, but I cannot seem to make an environment map--spherical or otherwise--that doesn't have distortion at the poles.

The most common tutorial I've found is using the Polar Coordinates distortion filter in Photoshop, but there is inevitably stretching and fading at the upper and lower poles when the resulting map is brought into MAX; if I'm trying to do stars, it's especially bad because the stars often become all-but invisible.

And, as I say, pre-built maps don't get the job done, either.

Has anybody ever solved this? Or are we in just-get-over-it territory, here?

(And, for the record, in case it was solved in later versions, I'm on MAX 2013. I could afford to purchase this software once, and never since, so...)

[RobH2]

I would say start from a "known good spot" by downloading a free HDRI map from here or some other site:

https://hdrmaps.com/freebies

Put that in a scene and setup the environment properly. You didn't mention your render engine so you'll need to research the correct setup for the engine you are using. See if one of the "known good" HDRI maps works properly. If so, then Max is behaving. 

Now, to get a spherical star map you are going to have to create scene that has a sky filled with stars and render that out as an HDRI in the proper way as an equirectangular map. Its height will be exactly 1/2 its length in pixels. These kinds of files have severe stretching along the top and bottom edges so that the when the merges together at the poles, they don't pinch.

You can't just take an image into Photoshop and put a polar filter or something on it as it will create pinching. 

I'd test a "known good" HDRI and then start from there figuring out how to next, generate your own. There is plenty of software out there to help you. 

[Anonymous]

Actually, it turns out that Blur settings were the culprit.

I've never seen Blur settings on a map do much at all, except perhaps cover over a seam between tiled images. But if you crank it down as far as it will go on an environment map, that distortion seems to disappear.

Granted, this also seems to add to render time a fair bit, especially if pointed at the poles, but that horrible stretching and fading isn't there anymore.

[RobH2]

Glad you solved it and your fix is something new that I'll keep an eye out for should I have an issue like yours one day.