HowTo_Measure

How to Measure 2d Images

One-time Preparations

The precompiled version of FacePalm is a single executable intended to be used on a modern Windows computer with .net 4.5 installed. It does not require a complex installation procedure let alone administrative rights, in fact you can put the executable file just about anywhere you want. It should even work as "portable app", i.e. directly from a USB-drive (in which case you should cultivate the habit of backing up your data somewhere else).

The recommended way to prepare FacePalm for use is to create a dedicated directory for your project and fill it with

• a copy of the executable program into this directory
• if required, a suitable "calibration image" like the provided splash.jpg, rename it to splash.jpg
• the definitions file used in the current project, rename it to Definitions.csv
• the images to be processed

If you start FacePalm by double clicking on its icon, it will then

• load Definitions.csv
• load splash.jpg and be ready for use.

Usual Workflow

Load Picture

Use the File menu to load a picture into the workspace. FacePalm supports the standard formats JPEG and PNG. Loading a picture will erase any points that are currently set, so make sure to save your work before loading the next image. You can find options for zooming in the View menu and use the scrollbars to move the visible viewport over the image.

Locate Points

The list on the left hand side shows points, segments and lines. To place a point, select it in the point list, then click the left mouse button on the correct location in the picture. If you "just missed it", don't move the mouse pointer yet. Instead, hit the space bar on the keyboard to select the same point again and wiggle the mouse pointer a bit and click the left mouse button again to improve the placement.

Once a point has been located, its name is highlighted. If both points of a segment or line have been defined, the name of the segment or line is automatically highlighted and the segment or line becomes visible. Once they are defined you can hide and show individual segments and lines by clicking on their entry in the list.

To select the next point, you can either left-click in the list or move the selection with the up/down arrow keys on your keyboard.

Save your Work

The recommended way to save your work is Save session... in the File menu. This command will create a zip archive containing

• the unmodified image file
• the current set of definitions
• the current set of points

Not only does this allow you to continue working on the same picture at a later time, maybe even at a different computer, it is also a reliable method of keeping sufficient records for reproducing the measurements at any time.

Export data and pictures

Once all points are placed, you can export their coordinates and the lengths of the defined line segments to a csv-file for further processing with suitable statistical methods. If you choose to save in a "new" file, a leading line with column headings will be created before the data is written. If you choose a file that already exists, only a single line with the data of the current picture is appended to the file.

You can also export the image including currently visible objects for presentations or publications. Note that the saved image is just the painting, carrying considerably less accessible information than the zip archive mentioned above. You can hide and show individual segments and lines by clicking on their entries in the definition lists.