How to measure on an image from Google Maps
Click on Image > Import from Google Maps, enter the address and navigate and zoom in/out to get the most effective image of the place you wish to measure on. When the image is in position, click on Snapshot to load the image and start measuring.
The image is automatically calibrated according to Google Maps settings. When the image is loaded you can start measuring directly.
You have the option to us an image from Google Street View. When you have found the address in the Google Maps application you take the orange man on the left side and drag him onto the street. You can now navigate around the street with your mouse to get the most effective image of your measurement.
When you have selected an image you press Snapshot. You can now calibrate the image and then start measuring.