Point the camera at a real surface. Field Measure Pro uses WebXR hit-testing to track the environment live. No photo and no calibration photograph are required.
How it works: move slowly until the green reticle locks to a surface, then tap Place Point (or tap the screen). After the first point, move the phone and the distance updates live to the current surface point.
Requirements: HTTPS, a compatible Android phone, current Chrome with WebXR/AR support, and Google Play Services for AR. Results are estimates, not professional survey measurements.