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I'm creating the classic "Pan away from Earth" animation and would like to arrange it so that detail levels are more or less constant throughout the animation.

The problem I'm having is figuring out how to map these textures on my sphere in such a way that they line up properly.

Right now I'm borrowing the full size NASA Earth image textures, which work fine when my shaders are not too complex. However, when I add several more layers (clouds, bump map, normal map, my own additional textures and so on) at the same resolution, my 4gb GPU can't handle the strain.

To solve this, I'd like to create several different resolutions of each texture, and then stack them on top of one another in a single texture. I would then crop the higher resolution textures around those points near to where my camera will begin its "journey" to reduce the GPU strain. I would then map the whole Earth with a relatively low resolution texture for when it is needed.

Unfortunately, I cannot figure out how to map the "cropped" images. Right now, I'm cropping them in Photoshop before importing them. However, when I map them "spherically" they are stretched to the full size of the sphere. Playing with the texture mapping utility is difficult, and sliding around UVs manually is hopeless.

Is there a simpler way to do this within Blender?

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  • $\begingroup$ As long as the images have the same proportions (even if they are different resolutions), the UV mapping would work for different images. $\endgroup$ – cegaton Nov 20 '17 at 6:50
  • $\begingroup$ I think his problem is that he is cropping out a part of his HD image so that he can use a smaller sized file for his close ups. This cropped image cant use the same mapping technique because he only needs it on a smaller part of his model. Not sure about this, but if he were to use the uncropped HD image and cuts out all the faces he doesn't need to show on the "close up model", would that lessen the strain on his GPU? $\endgroup$ – TomTr Nov 20 '17 at 7:20
  • $\begingroup$ TomTr, that is correct. The problem I am having is getting the cropped, higher resolution, image aligned with the full-size, but lower resolution one. There is no easy way to map the smaller image, short of trial and error. Moreover, the "spherical" mapping that I am doing (I am not unwrapping UVs, but simply applying "spherical mapping" in the Image Texture node- which works perfectly with the NASA textures) does not map a smaller image in the same manner as a full-sized one. $\endgroup$ – Brad Hoehne Nov 20 '17 at 15:53
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It sounds like your images have some blank space once you've reduced the resolution. If you simply get rid of that space and make the whole image smaller blender should automatically scale the UVs relative to the image size.

What I mean by this is that if your UVs on the full resolution textures go right up to the bounds of the image, if you have a texture at half that resolution and size the UVs should just be scaled down and still go right up to the bounds of the image.

You can see how I mean if you take a lower resolution image that has no empty space and replace a high res image with it.

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  • $\begingroup$ The problem is, I want multiple images at different resolutions so that I can start very close to the sphere and see lots of detail, and have less resolution on the parts of the sphere that will be seen when I am far away. The problem is, I do not want the entire sphere to have extremely high resolution, only a small portion of it, to keep the engine from crashing under the strain of large images. I can't figure out how to do this. $\endgroup$ – Brad Hoehne Nov 21 '17 at 4:23
  • $\begingroup$ Cycles shouldn't slow down too noticeably with larger images, however it will require a bit more vram to render. But with 4gb you should be fine. I would simply use the high res texture for the whole planet and just lower the whole resolution as the camera pans away. I've rendered planets in the past on a 2gb card and used several 4x8k images with no issues. $\endgroup$ – Brenticus Nov 21 '17 at 4:37
  • $\begingroup$ Brenticus, I'm using a 10.8x21.6K image, which allows for extreme closeups. It's not so much a matter of blender slowing down, it's a matter of the card running out of memory with a diffuse layer, a gloss layer, a cloud layer, and a bump layer all this size. I could reduce the cloud size, but the bump and gloss layer are critical for the effect I'm going for. I'm trying to get multiple UVs to work, but it's next to impossible to unwrap in such a way that the images line up. $\endgroup$ – Brad Hoehne Nov 23 '17 at 18:11

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