Hello everyone!

I've been playing a Rogue Trader Campaign with a group of friend for a little while now, using Roll 20 (Since meeting up in person is not really an option). 40k is a big universe, particularly when the Players hace access to a Spaceship and can fly wherever they want. So on multiple sessions I wouldve loved to have some Maps avaiable. Roll20's Assets didnt really appeal to me, since you'd have to buy around 10 different Tilesets to build something for different situations, so I started thinking about drawing my own Maps. Setting up a Star System in Photshop was fairly easy, and even making Planets wasnt too much of an issue (Plenty of Tutorials around for making those in PS). The real problem came along when I wanted to get into making ground maps, particularly "tactical" ones for the party to look at on, say, a Holoscreen or some such. Since Rogue Trader can feature some grand scale war scenarios it would help a lot to be able to prepare some of those.

I tried looking for Tutorials, Software and the like to get started. But frankly, there is so much that I have no idea where to start. As mentioned I got Photoshop, but I have no idea if that is suitable to draw City or Planet Maps. There arent many Tutorials around for drawing sci-fi style Maps, most of what I looked at was aimed at a Fantasy Setting.

So basically I'm looking for advice and suggestions you guys might have for this kind of stuff. Also ofc software recommendations, with Open Source being preffered, altough I recognize that there might not be a lot of good free stuff around.