Dangerous? First, obviously you have not kept up with image processing otherwise you would know that Photoshop IS used for court evidence. Its frequently used to make laboratory and field images more visible for a jury. Second, as long as long display a scale in the scene and try to represent items in the scene as proportional to one another you are fine. Third, no matter how meticulous you are you always have to state that the measurements in the sketch are not to scale. That is because of the chance of incongrutous measurements when you record your findings at the crime scene. Fourth, a sketch or 3d view is never used without photographs to document each type of evidence found at the scene.