Thanks... yes most of my stuff is experiments
I actually like both versions of the image above. Zooming in with the spherical star image makes the stars really soft, but it kind of gives the render a telephoto look... pin sharp terrain, softer clouds and even softer stars.. giving an impression of depth.
So for animating the star field I produce a high res equirectangular panorama with south in the centre of the image. I then load this several times into a new PTGui project. In my case I want the south pole to be 53° above the horizon so I set the pitch for all input images to 53°. I then increment the roll of each input image slightly for the rotation, outputting a "smaller" panorama as individual layers. This gives me a numbered sequence of images.
In TG2...
1: Add a constant scalar next to the background node (for easier acess)
2: In the internal network of the background, remove the shader and replace it with a default shader.
- set the image projection to spherical and increase the luminosity
3: Above that add a multiply colour node
- connect the constant scalar to one input
- connect the output to the
colour and luminosity functions of the default shader [edit] (connecting the image to the colour function via the smae multiplier as the intensity was a bad idea, reduces saturation if you use a low multiplier at night).
4: Add an image node, replacing the sequential number (I'm using 4 digits) with "%04d" (filename%04d.tif")
- set the projection to spherical [edit] FlipX! [/edit]
... and you're done.
Increasing the luminosity helps the stars punch through thin cloud but it will also make it show up in "daylight" This is why I added the constant scalar/multiply nodes. This provides some control so that you can tweak the intensity of the stars and sunlight strength separately, giving you the control you need through twilight in an animation.
