Hi. I'm just playing around to get an terrain image into Kstars. In principle it works well, I've made a png file of my observatory and can see it in Kstars. I also created an artificial horizon based on the picture.

Now my question: its not possible for me to get the "whole" sphere of the sky (since there is much clear sky ). So what I did is the following: I reduced the image size in x to 4096px (since the original was roughly 30000px). The height of the picture then was about 1100px. Somewhere in the internet I found that at least for stellarium the ratio should be 2:1. So I increased the picture size to 4096x2048px with the north point in the center (altitude 0°, latitude 0°)

Is this method ok? Because if I dont use the right ratio this would stretch my artificial horizon.

The aspect ratio of the terrain image doesn't matter. What the code does is assume that the left column of the image corresponds to Azimuth = 0º and the right column Azimuth = 360º, the bottom row corresponds to elevation -90º and the top row is +90º. It linearly interpolates all the pixels between the extremes. It then offsets everything by the "Terrain image azimuth/altitude correction degrees" parameter in settings.

Please let me know if you think you see otherwise.
Hy

Thank you Hy for the explanation. After reading I dont know why I saw that by myself

I think the aspect ratio wouldnt matter IF I would have a full sphere (but it will come out 2:1 for quadratic pixels). In my case I had not the full sphere and had to add the missing areas in a drawing program. That brought me to the question of the aspect ratio.

So in Azimuth direction we have 360°, in elevation 180°. This explaines of course the ratio of 2:1 (in the case of quadratic pixels). And if I set the north direction and horizon to the center I minimize the correction values (in best case both are zero) in the settings in Kstars

Hi
and how can we associate N and S on this picture.
do we need to start capturing on some specific position and do a 360° ?
regards

Hi,
have a look at those two youtubes:


(german)

according to the second video I used Image Compositor Editor (Microsoft), where you can adjust the orientation of the panorama. I just marked the horizon/north direction before starting taking photos.