Use Snap, guides, and grid to reduce manual error

Snap: common vs step (and when to turn it off)

• Use common-angle snap when you expect clean angles (like 30°, 45°, 60°, 90°). It’s great for quick checks and diagrams.
• Use step snap when you need a controlled adjustment (like 1° or 5° steps) without drifting.
• Turn snap off for the final fine-tune when you’re between steps or the image edge is slightly irregular.
• Snap won’t fix a tilted photo. If snap feels “wrong”, align the image first so your baseline is truly horizontal/vertical.

Guides: keep a baseline when the edge is unclear

• Use a guide line as your baseline direction when the image doesn’t have a clean straight edge to follow.
• Add a second guide to match the other side direction. This reduces the “which pixels am I following?” problem.
• If the value jumps, zoom in and reposition the vertex first; guides help, but vertex placement still matters.

Grid: alignment and sanity checks

• Use the grid to align a known horizontal or vertical reference before measuring (floor line, page axis, CAD axis).
• After you measure, the grid is a quick sanity check: does the baseline look truly level relative to the image?
• If the photo has perspective distortion, treat your number as an approximation; use the most “straight-on” reference you can.

A simple workflow that stays stable

1. Align the image first using the grid (horizontal/vertical reference).
2. Place the center exactly on the vertex and zoom in so the corner is clear.
3. Turn on guides when you don’t have a clean edge for a baseline.
4. Choose snap mode: common for quick clean angles, step for controlled adjustments.
5. Fine-tune the last degree with snap off, then export once the reading matches the edge.