Printable scale marker

A printed marker gives your map a real-world (metric) scale. It's optional: without one, maps are built with an approximate or unknown scale. Print one or both markers, place them in the space, and make sure they're visible while you record your walkthrough. Back to the VMAP docs.

The print dialog lets you choose a printer or Save as PDF. Use A4 or US Letter.

Before you print

1. Print at 100% / actual size. Turn off "fit to page" or "scale to fit" in the print dialog.
2. Check the printout with a ruler: the 100 mm check line must measure exactly 100 mm, and the black square should measure 160 mm. Use the black square's measured size as marker_size_m (for example 0.160).
3. Matte paper works best (glossy paper reflects light). Keep the sheet flat, and don't write or draw in the white margin around the square.

Placing the markers

1. Tape the marker flat on a wall at about eye height, where nothing covers it.
2. While recording the walkthrough, make sure the marker is fully visible in several frames, from different angles and distances.
3. Two markers (ID 0 and ID 1) in different parts of the space improve accuracy. ID 0 defines the map origin. Use each ID only once per site.
4. You can remove the markers after mapping. Localization doesn't need them.

Preview

AprilTag 36h11  ·  ID 0  ·  black square 160 mm

This line must measure exactly 100 mm. If it doesn't, reprint at 100% scale.

Tape flat at eye height. Keep it fully visible in several frames of your walkthrough.

AprilTag 36h11  ·  ID 1  ·  black square 160 mm

This line must measure exactly 100 mm. If it doesn't, reprint at 100% scale.

Tape flat at eye height. Keep it fully visible in several frames of your walkthrough.