Aerial image and height data
The roof editor uses two layers from Google Solar for the home — an aerial photo at about 10 cm per pixel and a 3D height map of the roofs and trees. You trace on the photo; the heights give each face its pitch and direction and show where shade falls.
Everything you draw sits on real measurements of the home — not on a guess from a flat picture.
The aerial photo
A top-down photo of the home and its neighbors, about 10 cm per pixel, covering an area about 70 m (230 ft) across. You trace the roof faces on it. The top bar shows when Google took it and how sharp it is, for example Imagery Dec 2, 2023 · high quality.
The photo shows the roof on that date. A new addition, a new roof, existing solar panels or a tree cut down since then won’t be on it — check on site.
The height map
Google also measures the height of every point of the roofs and trees around the home. Cali-Graf uses it to:
- measure the pitch of each face you draw and which way it slopes — see Roof pitch: measured or set by hand and Roof face direction;
- tell ridges, hips, valleys and walls apart where faces meet — see Edge types: eave, rake, ridge, hip, valley;
- find chimneys, vents and skylights — see Detect obstacles automatically;
- work out the shade from trees, neighbors and chimneys on each panel for the calculation.
When the data is weaker
With medium or low quality imagery, outlines are blurrier and heights less exact. Trees over the roof or a fresh change to the house can confuse the measurement too. The editor then says so in the face’s settings — Google heights are uneven on this face — check the pitch and pick it if it looks wrong. — and you can set the pitch by hand.
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