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Knut
05-12-2002, 03:19 PM
Hi! I got a question in this thread:
http://www.cgtalk.com/showthread.php?s=&threadid=6980&perpage=15&pagenumber=2
on how i made my seamless spherical enviroment map.

And here is how:

1. Open Lakerem.jpg (Included in 3dsmax, but just open any bitmap you have.)

2. Use the offset filter in PhotoShop, i used -400 Horisontal. It's best to offset by 1/2 the witdth of the image. You then need to clone or use any tools to remove the seam.

3. Seam removed!

4. Offset back to what you started with. I used Offset +400 Horisontal. You don't have to do that, but i did. And now we have a horisontal seamless map.

5. Now we need to make it a spherical seamless map. First duplicate the layer you have. Then use a polar coordinates filter and choose rectangular to polar. Then we see how the map will look if it's spherical mapped. And you see some distortion in the center of the image. This we will have to remove by cloning or any other tool. (Just ignore the distortion around the edge)

6. Seams and distortion removed. Remember that the center will be on top of your finished spherical mapped bitmap.

7. Apply a polar coordinates filter and choose polar to rectangular.
The you have a predistorted northern hemisphere. And you can stop here if this map is going to be mapped onto a sphere on only the northern hemisphere.

8. Hide the newly done layer and duplicate the original seamless layer from step 4. Rotate it 180 degrees.

Knut
05-12-2002, 03:29 PM
9. Apply a polar coordinates filter and choose rectangular to polar.
If there are any seams or distortions in the center of the image, then remove it by cloning or any method you choose.

10. Seams and distortion removed!

11. Apply a polar coordinates filter and choose polar to rectangular.

12. Rotate the image back again 180 degrees.

13. In Pohotoshop or the program you have, unhide the layer where you fixed the sky. Mix the sky with the map where you fixed the water with a mask, and you get the finished result:

14. Finished and ready to use as a spherical map.

Hope this makes sense. And if anyone have additions and better ways of doing this, then feel free to post it here. And comments are ofcourse welcome!

leigh
05-13-2002, 09:01 AM
Hey Knut, cool tips here :) I also described this process in the texture workshop. The only problem with keeping the filters applied though, is that applying more and more filters to an image actually destory it. What I usually do is copy the image to a new layer and apply the filter to that one, and then use it as a reference.

Knut
05-13-2002, 09:26 AM
Hi Leigh!

I've also noticed that photoshop does not have very good math behind the polar coordinates filter. I've read somewhere that panotools (the free stitching software) has better filters for doing this. I did never think about using the final image as a reference, good idea. I did actually do something to get around that problem. Though i didn't mention it in my tutorial. In the attached images you can see how the original is compared to the finished map.

1. The finished map as described in the tutorial above.

2. I scaled the original image 200% before step number one in my tutorial and scaled it back down after the last step.

3. Is the original untouched image.

This clearly shows how the filters affect the final result. If one makes a better mask that only applies the tweaked bits of the image to the original, the quality would be higher. Thanks Leigh for pointing it out!:thumbsup:

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