Measuring Basics

ImageMeter provides several different ways to enter measurements into an image:

• use a Bluetooth laser distance meter,
• measure on (scaled) PDF pages,
• compute the measure based on image geometry,
• just enter them manually.

Can we measure lengths in a photo automatically?

If you want to measure dimensions in a photo, you first have to understand that this is impossible without further information. Just consider two similarly looking photos. One is showing a real house and the other one a well-made model of the house. Both photos will look exactly the same, so it is clearly impossible to get absolute measurements from the photo alone.

How to do it nevertheless

In order to be able to measure absolute lengths in a photo, you have to provide at least one known reference size. ImageMeter can then use this given size to compute more dimensions in the image.

There are different tools in ImageMeter to provide this reference size. Depending on how the image is taken, you should choose the tool most suitable to the task.

• The Reference Scale is the easiest way that works if you have an image of a flat object. This is similar to the scale printed on maps. You can use this on scanned images, or photos of plans or flat objects, as long as the picture is taken without perspective.
• The Perspective Reference allows measurements on any plane in the image, even if they are perspectively distorted. ImageMeter will correct the geometry and compute the dimensions in any case.
• There is also the Perspective Length tool that allows to measure distances or heights along one dimension. This tool does not provide a reference for other measurements, but you can use the tool to carry out measurements in one dimension.