Frequently Asked Questions About Roof Pitch and Area Measurement
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Which units of measurement are available?
In Australia, a roof angle is expressed in degrees; in the US, roof pitch is most commonly expressed as how many inches the slope rises for every 12 inches of horizontal run. Both units of measurements are available in the new 3D Line and Area tools.
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Why are these tools only available in Obliques?
To find the pitch and area of a roof or structure, we need to understand where each measurement point exists in real world coordinates — that is, we need to translate 3D coordinates from a 2D image. Measuring in two oblique photos at different angles allows us to triangulate real world coordinates using the information from each photo, such as the camera position and location. It is then possible to mathematically calculate the pitch, area, and length.
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Can I use the 3D Line tool to measure a hip roof?
The 3D Line tool relies on being able to place the line in the exact same position in the second photo — which means it’s hard to get right on a hip roof. We advise you to use the 3D Area tool when you wish to find the pitch of a hip roof.
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Which version of MapBrowser do I need to access the tools?
Measurable Obliques, including the 3D Line and 3D Area tools, are available in the new MapBrowser.
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How accurate are the tools?
Accuracy is determined by two factors: the resolution of our imagery, and the accuracy of the user when drawing. Nearmap Oblique imagery has a vertical accuracy of 15cm. When tested on locations with known measurements, the 3D Line and Area tools are accurate within 2-3%.
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How can I make sure my measurement is as accurate as possible?
Zoom in when drawing to ensure you get a more accurate placement. You can start with any oblique image — if the default image doesn’t give you the best view of what you want to measure, simply select another photo from a different directional perspective.