Background and scale

What a background is

• A background is a drawing as a PDF, JPG or PNG that you trace the roof outline from.
• It is only an image under your drawing. FredIQ calculates from the drawn roof and the scale, not from the background.
• The file can be at most 20 MB. From a PDF, the first page is used.

Upload a background

1. In the editor of an empty roof, click Upload an underlay in the How would you like to start? card. At any other time, use Upload background in the editor's top bar.
2. Choose the file.
3. Set the scale, see the next section.

• Hide and Show in the top bar hide the background and show it again.
• You set the background opacity in the Background card in the left panel.
• You upload a different background with the same button. The drawn roof and the scale stay, but the earlier measurement does not belong to the new background: measure the scale again.

Do you have a drawing in DXF? The import takes over both the outline and the scale from the drawing, see Importing a DXF drawing. A roof with an uploaded background does not offer the DXF import, though. Create a new roof for the DXF drawing.

Set the scale from a known length

1. In the Scale card in the left panel, click Set scale. If a scale is already set, click Edit scale and then Measure again.
2. In the drawing, click the start and the end of a line whose length you know, for example a dimensioned edge. The point snaps to a corner or to the midpoint of a drawn edge; otherwise it lands exactly where you click.
3. Type the length in millimetres into the Real length field and click Confirm length.

The card then shows the measured length and the roof area. You cancel the measurement with the Esc key.

Measure the longest dimensioned length you can. A small error when clicking has the least effect on it. Compare the area in the card with the drawing.

Scale without a background

• An empty roof without a background has the default scale 1 px = 1 mm. You enter edge dimensions as numbers directly while drawing, see Drawing aids.
• You can also enter the scale as a number: in the Scale card, fill in One canvas pixel in millimetres and click Apply.
• When you upload a background to an empty roof, the default scale does not apply to it. Measure the background first.

Changing the scale of a drawn roof

• Changing the scale changes the real dimensions of everything that is drawn.
• Before the editor makes the change, it shows by how many percent the dimensions and the area will change. You confirm the change with the Change dimensions button, or you cancel it.
• Results calculated with the original scale are then no longer valid and need to be calculated again.

Where the scale is checked

• The Steps window contains the Set the scale step. When a background is uploaded but nobody has measured it, the step says that the roof is at the default scale 1 px = 1 mm. The area then does not match the drawing.
• Without a scale, the application cannot calculate the area, the slope design or the drainage assessment.

Pitched roof and facade

• The pitched roof editor has the same Scale card and the background upload in the top bar.
• For a facade, the background is uploaded the same way. Here the scale belongs to the image; the facade drawing does not change. In the Background card, you also place the origin on the bottom left corner of the facade.