Auto-Label Edges: how geometry names your eaves, ridges, hips and valleys, and why it leaves some yellow
Auto-Label Edges reads the planes you drew, works out which way each one falls, and types the lines two solvers agree on. Here is why some stay yellow and what to check.
Auto-Label Edges names a line when two separate geometry solvers, reading the planes you split the roof into, reach the same answer for it. Ridge, hip, valley, eave and rake lines they agree on get typed in one click; anything they disagree on stays yellow for you, and flashing lines are always yours to name.
A worked example: a hip roof with a porch
Take a plain hip main roof with a shed-style porch roof tucked against one long wall. You trace the outline, split the main roof into its four planes along the hips and the ridge, split the porch off as its own plane, and the right panel reads something like Edges labeled 0 of 14.
You press Auto-Label Edges in the Edges labeled card. On a roof like this, the result usually looks like this:
- The four eaves of the main roof, the ridge and the four hips come back typed. Every plane on a hip roof falls cleanly away from its neighbours, so both solvers read them the same way.
- The porch's front eave usually comes back typed too: it is the lowest edge of a plane that clearly falls toward the street.
- The two short side edges of the porch and the line where the porch meets the wall often stay yellow. A shed roof is a box with one slope, and from above a box gives the geometry very little to argue from.
A toast tells you how many lines were labelled and how many are left for you, with an Undo button. That is the whole interaction: one run, one undo step, and the yellow lines are your to-do list.
How the geometry decides
Both solvers work from the same thing you drew: the planes, seen from above. Neither looks at the photo, and it is geometry, not a model that learned from roofs.
The key idea is that every flat roof plane has one downhill direction. Once you know which way each plane falls, the line types follow:
| Where the line sits | How the planes fall | Label |
|---|---|---|
| Line shared by two planes | Both fall away from it, line level | Ridge |
| Line shared by two planes | Both fall away from it, line sloped | Hip |
| Line shared by two planes | Both fall toward it | Valley |
| Outline edge | The plane falls across it | Eave |
| Outline edge | The plane falls along it | Rake |
The two solvers get to the downhill directions differently. One works out a height for every corner of every plane and picks the falls that make those heights agree along every shared line. The other starts with the plane whose fall is most obvious and passes that evidence to its neighbours, since two planes meeting at a line usually fall as mirror images of each other. They make different kinds of mistakes, so when both reach the same label for a line, it is filled in. When they disagree, the line is left alone.
Why some lines stay yellow
Yellow is not an error. It means the geometry was not sure, and the tool would rather hand you the line than guess. The usual reasons:
- The roof isn't split yet. A lone outline has no shared lines, so there is no ridge, hip or valley to find. If you run it on an unsplit roof, the toast tells you to split the roof into its planes along the ridges, hips and valleys, then run Auto-Label again.
- Boxes and low sections. Porches, sheds, flat sections and bump-outs have few neighbours to compare against. Whether a side edge is a rake or an eave is often a coin flip from above.
- Walls. Step, headwall and sidewall flashing depend on a wall the drawing doesn't contain. Auto-Label never types flashing.
- Odd shapes. A short notch, a sliver plane or a line drawn at a strange angle can push the two solvers to different answers.
What it never touches
Lines you typed by hand stay as you typed them, even if the geometry would have picked something else. The run only fills untyped lines, so you can label the tricky parts first and let it do the rest.
The exception is a roof you reshaped after labelling. If you move corners or redraw a section and run it again, and some labelled lines no longer fit the new shape, a Your roof changed prompt highlights them on the roof and offers Update all lines, Only unlabelled lines or Cancel. Nothing changes until you pick.
A working order that saves clicks
- Trace the outline at the drip edge, the way the satellite measuring guide describes.
- Split the roof into every plane along its ridges, hips and valleys. This is the step that makes Auto-Label useful.
- Run Auto-Label Edges from the Edges labeled card or the ⋯ menu.
- Click each yellow line and answer What is this edge? yourself, flashing included.
- Glance at the typed lines in the edge chips: count the hips, look at the valleys, and fix anything that reads wrong.
- Set the pitch on every plane before you export.
Where you trip
- Running it before you split. You get a few eaves and rakes and a reminder to split. Split first.
- Trusting it on the porch. The low, boxy sections are where it is weakest. Check every edge of an attached porch or shed by eye.
- Forgetting flashing. The PDF's flashing footage comes only from the lines you type. If the yellow lines along a wall stay untyped, that footage is missing from the order.
- Reading "all labelled" as "all right". The toast counts lines, it doesn't check them. A wrong hip on a hip roof still moves your cap count.
- Undoing too late. The toast's Undo and the toolbar Undo both reverse the whole run in one step. Use it if the result looks off, then fix the planes and run it again.
FAQ
Does Auto-Label Edges cost credits?
No. It runs in the builder on the planes you drew; it doesn't send the photo anywhere, so it doesn't use AI credits.
Does it read the roof pitch?
No. It needs only the shape of the planes from above. You still set the pitch on every plane, and the roof area only counts once every face has one. The roof dimensions explainer covers how pitch turns footprint into roof area.
Will it change a line I already typed?
No. Hand-typed lines are kept. Only the Your roof changed prompt can update a labelled line, and only when you choose Update all lines.
Is this the same as an AI drawing the roof?
No. You still trace and split the roof. Auto-Label only names the lines afterwards. For the jobs AI does and doesn't do in roof measuring, see what AI roof measurement actually means.
The yellow lines are the point: the geometry handles the obvious lines and leaves the judgement calls to you.