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evolross
07-02-2007, 08:50 AM
I'm trying to create a model of the earth by using a sphere and downloaded images from visibleearth.nasa.gov (http://visibleearth.nasa.gov/view_rec.php?id=7102).

The downloaded images that I'm using are JPEGs and PNGs that range in size from 18MB to 120MB.

No matter if I use spherical mapping or use a UV map, when I load the image in the Surface Editor, it pauses, and then crashes Modeler everytime. No matter if its the JPEG, PNG, 18MB file, or 120MB file.

Does Lightwave have some kind of image size limitation, or should I be breaking the image down into smaller pieces or something?

I've had no problems with smaller images and my machine is a quad-Opteron, 3GB RAM, with a Quadro FX 4500 so isn't a resources issue.

Lightwolf
07-02-2007, 08:59 AM
The images are very likely to be compressed, and use a lot more memory when actually loaded (LW needs to uncompress the images to be able to access them).

Plug: You could of course have a look at infiniMap, and use it for some really large images (-> http://www.geotorrent.org) ;)

Cheers,
Mike

evolross
07-02-2007, 03:02 PM
When saving the 19MB JPEG as a TIFF, it saves out to 683MB. When I try to apply this to the sphere, it still expectedly crashes.

Is there some kind of approach to this? Like dividing the image into smaller chunks, or simply using a smaller image file?

What is the typical approach when wanting to model an object with high resolution textures?

(Thanks :o )

Lightwolf
07-02-2007, 03:14 PM
When saving the 19MB JPEG as a TIFF, it saves out to 683MB. When I try to apply this to the sphere, it still expectedly crashes.

Yeah, so that seems to be the uncompressed size


Is there some kind of approach to this? Like dividing the image into smaller chunks, or simply using a smaller image file?

Either way really. Chunks and only use the bits you need... or smaller images.


What is the typical approach when wanting to model an object with high resolution textures?

There is a reason why I developed infiniMap ;) So far I've found that anything larger than 200MB causes problems, per image (many small images are less of an issue).
Stepping up to 64bit may help as well (depending on the platform you're on).

You can also turn of mip-mapping for the image (in the image panel), which eats up an additional 50% of memory compared to the base memory used by the image (in your case another 340 MB).

Cheers,
Mike

Lightwolf
07-02-2007, 05:14 PM
Hah, I almost forgot, this is a more in-depth article on the topic:
http://www.lightwiki.com/Optimised_image_use

Cheers,
Mike

evolross
07-03-2007, 09:46 AM
After reading the article, I converted the TIFF to PNG. I then divided the PNG into four equal parts, each being a fourth of the overall rectangular globe image.

The images are now successfully loading :) but now I'm having trouble correctly applying them to my sphere.

The way the texture is laid out, it's a rectangular image of the globe that logically looks like it should be spherically mapped to the sphere on the Y axis (see visibleearth.nasa.gov (http://visibleearth.nasa.gov/view_rec.php?id=7102) for an example) . When I cut this in fourths, the images sort of get applied the way it should on the fourth of the sphere I selected, but I can never get the size or position quite right. It's always distorted and not using all of the image. It gets somewhat better when I use "Automatic Sizing" but that still doesn't size it right.

I also tried creating a UV map, but neither spherical nor atlas lays out the polygons appropriately for the rectangular fourth of the globe image.

I feel stupid because it seems like texture an earth would be really easy. :stumped:

Giacomo99
07-07-2007, 01:52 PM
Is there a reason why you need all that resolution? If you're just doing an animation, it's probably overkill. I'd sample down the image to the minimum size you need.

evolross
07-10-2007, 02:16 PM
I'm going to have a shot where I rotate around the earth and I would like it to be high resolution. I'll play around with the image size and see if I can get something that's lower resolution but still looks good in the shot.

evolross
07-10-2007, 03:14 PM
So I took the uncompressed JPEG which is a 600MB TIFF and reduced it by 50% in Photoshop which resulted in a 150MB TIFF file which doesn't crash Lightwave and looks rather nice.

Thanks for the tip. :thumbsup:

4dartist
07-13-2007, 03:37 PM
If I was going to UV map your 4 cut images over the sphere I would make a spherical UV wrap around the sphere so the unwrap would look like a blanket All square and even looking. You'll get some mess up at the top where the triangles are. To fix this: delete the cap on top and bottom of sphere, grab top row of points and use extender to replace the old cap by scaling the points together but not merging, this way when you use Spherical UV unwrap you don't get triangles at the top and bottom of UV, instead you get perfect unwrap.

THEN: Scale the UV to twice the size exactly. Then copy the UV 3 times and move each one so its respective area you want to texture the image too is over the correct quadrant of the UV map. So one UV will have top left over the image. The next would have top right, bottom left and finally bottom right.

In my head that would work. ;) Not sure though i've never done it but it sounds simple enough and i think it will work. Might be fun to try anyways.

Ben