Tutorial: Zonal statistics and area computation
5. Calculate area and perimeter of parcels
Often it's useful to know the area and the perimeter of agricultural fields. In this section we'll add the area and perimeter to the attribute table. We'll also convert the area units.
1. Open attribute table ndvistats layer
2. Click 
to open the Field Calculator dialog.
3. Type Area at Output field name and choose Decimal number (real) for Output field type.
4. In the middle section, expand the Geometry functions and double-click on $area to add it to the expression. You can read the help string on the right side of the dialog.
5. Click OK.
6. Check the new Area attribute.
7. Repeat the steps to add the perimeter. You can use the $perimeter function in the expression.
- What are the units of the calculated area and perimeter?
8. Use the Field Calculator to create a field with the area in hectares.
9. Toggle off the editing and save the edits.
