I've been playing around with Terragen for a while to create small environments, but one of my long-term projects has been to create a "living" planet. Part of that includes adding cities, and so I set to work on creating a plausible setup for displaying the effects of cities from afar (e.g., light pollution and orbital viewing). To test out my arrangement, I decided to plot 100 of the continental U.S.' largest cities and compare my output with well-known "Earth at Night" satellite composites.
I have attached the result, and I'm pretty pleased with the outcome. Tweaking is certainly needed, but I've decided to add this to the long-term project folder. The goal will be to plot the largest 400 cities (which ought to help fill out the glarlingly dark northern and southeastern portions of the country).
Let me know what you think and if you have any tips. A couple of forum searches didn't turn up a lot of similar projects; but if you know of some useful threads, point me in the right direction.
A search for "earth lights" on google, will give you the image you need.
Load it into a image map shader with spherical projection and add the size of the planet as the position.
Then plugg this one up with a default shader. (luminosity i think)
This is what i foud out when i tryed creating earth seen from space.
Shure other ways exist (with terragen there is almoust 2 or more ways of doing the same).
Addded one i did a fiew months ago.
Everything found on this wonderful forum.
All the countrys r in there, just have to rotate the camera around the planet.
Download earth maps, elevation maps, night maps and cloud maps and add to the default shader, and attach it to the planet shader.
Cloud map is attached to the cloud layer as a density shader.
Thank you for the tips, microwar. Image wrapping is still a bit of a problem for me, but I'm getting the hang of it.
I think I should clarify the origins and purpose of the project a bit, though. I wasn't setting out to recreate the Earth at night, per se. What I wanted to do was be able to "realistically" place cities on a generated planet (example of what I'm trying to accomplish in the two pics attached - before and after). Although I could put a light source, plug in values until it looked good and then call it a day, that's just not how I roll. So I took data from some government reports which calculated energy consumption in the U.S., and applied that data to U.S. cities; then I took the outcome and made approximations to light sources in Terragen.
Since I was using U.S. data as the basis for the project, I created the map of the U.S. at night just as a proof of concept piece, i.e., I wanted to be sure that the formula I came up with worked in a realistic manner. For the most part, it has; so I've decided to continue the project beyond a mere test and into something full blown, and I thought it'd be a neat thing to share.
The other value that this project has for me is that it serves as a kind of study for migration patterns: How cities group together around each other and terrain (e.g., densely populated coasts and river basins versus open plains, deserts, and mountain ranges). That should also help when I set about populating the final product.
Tips-wise, I think it would be helpful to learn how I can make the cities appear less spherical, since the light source is omnidirectional.
Thanks again for the feedback.