You have loaded a city scene in your virtual studio, have selected its center of attention, have placed and posed your main actor(s) within that center, have set up its lighting, the rendering camera position; the scene still looks empty; it is time to call in your extras (crowd actors) for their acting job for providing the proper ambiance of that scene and for filling that creepy void. Note: I recommend that you group your city and its city props with a root invisible object or group object, then that you translate that group in a way that your center of attention is positioned at the global origin position of your virtual studio coordinates. It is then much easier and faster for positioning any other props and actors within and around that center. I also recommend, for a city scene, that you pose initially each actor with a standing start position; it is then easier to place them in such type of scene, since there will be many actors there that would be close to each other. My Crowd People sets contain outfitted figures in a neutral standing position. Build your crowd starting near or within the center of attention ... and near the rendering camera, then add other figures further and further away from that center. Start loading the most polyvalent extras (from set 7 ideally, in one click for each actor) and place them around your main actors and between the main actor(s) and the rendering camera, if needed to be, something between 2 and 12 extras. Orient them and pose them in a way that makes sense around that center. Let's identify them as the "near" extras. Then do the same with extras that will be located further away from that center. These actors will usually be less versatile and less heavy on computer resources. You will find out that there are many places, as seen from the rendering camera, that are hidden by the already placed actors. You place the other extras in places that are not hidden; this is why the position of the rendering camera should be decided early in building your crowed scene. Often, with only 20 to 30 actors, the crowd might look to be populated by a hundred actors. Further away from that zone, you might add either billboard actors and/or static prop actors and/or background/faraway actors, when it becomes difficult to distinguish their features. Readjust the layout if needed to be. I think that you are aware that the layout is not necessarily definitive, after the Acting Phase, you might want to translate or turn some extras, you might also reposition your rendering camera, you might even add or remove a few extras. The above picture shows an example of what it looks after the layout phase and before the acting phase. I have removed to the main actor in order to focus on the crowd buildup phases. All actors in the picture are from my Crowd People Set 7 freebie.