Final answer:
Two effective variations for crime scene sketching are elevation drawings and cross-projection sketches, which allow for detailed documentation of evidence on vertical surfaces while filtering out unnecessary background details.
Step-by-step explanation:
Two variations in creating sketches that enable a crime scene technician to document evidence on vertical objects include elevation drawings and cross-projection sketches.
Elevation drawings are used to represent the side view of vertical structures, allowing for the clear documentation of evidence found on walls or doors.
Cross-projection sketches, also known as exploded views, involve unfolding a room’s walls onto a single plane as if the room were a box with its sides laid out flat, making it easier to map evidence located on different vertical planes within a single sketch.
These methods help in focusing on important evidence without the distraction of background elements, much like a geologist would use sketches to focus on a fossil's details in a cluttered environment.
Unlike photography, these techniques allow for the removal of extraneous details and the addition of annotations and measures directly on the sketch, thus providing a more detailed and tailored reconstruction of a crime scene.