Adjusting proportions and adding new objects to match sketchover:
In photoshop I set the sketchover to 50% over the original model render.
In Modo/3DS/whatever, I have two viewports set up: one for modelling, one with the cameraview that I rendered and sketched over previously. This way I can check the cameraview against the 50/50 reference image for consistency in real time. Alot more accurate than eyeballing it and easier too.
Trying to get my details right. I need to do alot more research on the VASIMR engines. Trying to find the right balance between truthful to the technology and interesting to look at.
Also working on the human scale issue, realized that this thing is way bigger than 15m I had originally thought. more like 25m. For reference the space shuttle is 50m. This is the airlock hatch + handrail detail. Still needs more I think.