So finally you have decided to get a golf simulator
The most important thing you need is a big room, at least 5 by 7 meter. Please note that not all simulators require that much space but most of the simulators require a spacious room for proper play. Do not think that it would occupy your so much space, think it as if it can also be used as a home theater to watch movies and other stuff for entertainment. If you are planning to share some room space for your golf simulator, make sure to surround it by enclosure to keep the ball from going out everywhere.
Once you are done with the enclosure, you can setup the computer system at a point which is close to the player but at the same time should not interfere in the game-play i.e it should be away from the hitting zone. The most appropriate place for it would be attached to the wall in front of the player. Do keep it protected from the ball, as a direct impact can do some serious damage to the screen of the computer. You will have some kind of sensors connected to the computer to record the swing path and other technical details. Depending on the type of sensors it can be placed, for eg: if the simulators use high speed cameras, it can be mounted on the roof of the enclosure.
A projector can be placed at the extreme end of the enclosure on the roof, it can be adjusted as per the screen size and the projecting angle of the projector. This will be connected to your computer system to project golf course image from the simulator software. After setting up the projector you will need a projection screen, which is good enough to resist the hits of the golf balls. Ideally this would take all the front area of the enclosure. After you are done with all this setup, you will also need light-box as the sensors don't work properly in less light. Depending on the specification of your simulator, you can setup the light-boxes. It should ideally be at the center of the roof.
Once you setup all these, you no more need the clear sky to play golf. You can play golf whenever you want, even in short breaks without even leaving your home. Being very high-tech, some indoor golf simulators are even expensive than a high end car. But if you are into serious golfing and are looking to improve all aspects of your game, it's a small price to pay.