Tutorial | Rotate and scale a scanned floor plan in Adobe Photoshop
In an ideal world you will be given a nice clean .dwg or .dxf file, or even a .pdf of your floor plan to get started with. However you’ll often get a scan or (even worse) a fax of your floor plan. The tutorial below will show you a precise way to rotate your canvas and set your drawing to a working scale.
Rotate your floor plan:
This is an example of a scanned floor plan that needs improvement; to start it’s tilted and has no scale. Let’s begin by rotating the floor plan.
The best way to make sure your plan is rotated properly is by using the Measure Tool.
- Select the Measure Tool (hidden under the Eyedropper).
- Draw a line with the Measure Tool over a line in your blueprint to measure its current angle.
- You can read the measured angle in the Menu Bar.
- Go to Menu > Image > Rotate Canvas > Rotate Arbitrary. The angle you just measured will appear automatically in the text-box. Just click OK and your drawing is rotated.
You can check if the rotation angle is correct by dragging guides from the rulers into your drawing (if you can’t see rulers in your file go to Menu > View > Rulers).
Setting the scale:
Your image might have a high resolution but that doesn’t mean it has the right scale. The following steps ensure that a print at 300 dpi will result in a scale of 1:50 (meaning 2 cm on your print will equal 100 cm in reality). The Plan Symbols Collections are drawn at 300 dpi and have a scale of 1:25 and 1:50.
Resolution and Rulers:
Go to Menu > Image > Image Size. Make sure Resample is turned off and Resolution is set to 300 pixels per inch. Click on OK.
Go to Menu > Edit > Preferences > Units & Rulers and set Rulers to cm.
- Find a known length in your drawing. In our example this is 210 cm.
- Select Measure Tool.
- Measure the known length using the Measure Tool.
- You can read the measured length in your drawing in the Menu Bar, 3,06 cm in our example.
You can calculate the scaling percentage using the following formula:
The formula for our example results in a scaling of 137,254% :
Scale your image:
Go to Menu > Image > Image Size. Enter your scaling percentage and click on OK. Now your floor plan has a scale of 1 : 50.
Working with the grid turned on in Photoshop will enable you to work more precise. Objects and selections will snap to gridlines and you can quickly see dimensions if the grid settings are correct. To turn the grid on go to Menu > View > Show > Grid.
The following steps will ensure the gridlines represent meters and centimeters.
Go to Menu > Edit > Preferences > Guides, Grid & Slices.
Set a gridline every 2 cm. Now the thick gridlines represent meters.
The Subdivisions are the thinner lines in between the gridlines; 4 subdivisions result in a thin line every 25 cm, 5 subdivisions in every 20 cm etc.
You can download these free rulers to scale for use in your floor plans from this link.
If you have questions feel free to drop us an email using the contact page.