I'm new to Terragen and I want to render out an erath with a cloudy atmosphere where I handle the density and distribution of the clouds with
a greyscale map. I saw several topics here in the forum and downloaded some files, but my clouds are still too small.
What I do is: I have an atmosphere which plugs into the input node of the cloud layer. A cloud fractal shader plugs into the density node of the
cloud layer. And finally I plug an image map shader into the blending shader node of the fractal. So far so good.
How to be sure so I have the correct size of the image map so it matches the planet size? I only have: 6.378e+006 for the earth radius.
Any help appreciated.
If your using global coverage cloud maps you need to set them up to spherical projection and set the "Position" to the same as the planets centre, ie 0, -6.378e+006, 0. Leave the scalling as it is, ie 1, 1. That should do it.
Also if your far enough away there is not much need to use a cloud fractal, just plug the image map directly into the cloud layer.
Hope this helps
Thanks for your fast respond cyphr!
I understand ... but what if come closer to the earth (I have to), how to plug all those nodes correctly together?
And most important how to control the generla size of the clouds which will be masked by the map?
Thanks a lot
Your setup is correct as you've described above. It can be much more complex but that is the starting point.
The size of the clouds is controlled on the scale tab of the cloud fractal shader.
The default is setup for close up shots. For planetary scale shots I would increase the Feature scale, the Lead-in scale and Smallest scale by a factor of ten (type an extra "0" after each value) and work from there.
I would also increase the cloud layers thickness to maybe 1500.
All this is of course highly simplified and your project will have it's own specific requirements and artistic choices but the above should get you going.
Perfect! Thanks cyphr that's a good point to start with my project.
Thanks for the help.