I have two textures, one that is NASA's “Blue Marble” image that covers the whole Earth, and the other is a smaller, more detailed satellite image of a much smaller area, i.e. the size of a U.S. state. I want to start out by looking at the whole Earth, and then zoom in to the smaller area, as seamlessly as possible.

I don't really know how to approach this but I think there are two problems here. I'd appreciate advice or pointers on either one:

1. How to show multiple overlapping textures at once on the same sphere? I tried using the Layer SOP but couldn't get it to work, and am not sure if that's even the right approach. I know how to use the lat/lon positions of the imagery and show each texture correctly-placed on its own separate sphere, but not how to show both simultaneously.

2. How to smoothly blend between the two textures so that the edges of the smaller texture are not super-obvious? I could get some more in-between resolution imagery for a smoother transition between the world-scale and state-scale images, but I wouldn't know how to get those to play together nicely, either. Can I somehow implement my own mipmapping in Houdini or externally? Or is there some sort of “texture blend” operation I can use?

Hi, for this kind of effect, I would most likely render your planet twice, once with each texture, and blend them in comp. To have the edges not be obvious, you are going to need an Alpha channel on your more detailed texture, with a smooth transition from white (opaque) to black (transparent).