MAPaint User Manual:
Using a Graphics Tablet

  
Using a Graphics Tablet

MAPaint is designed and intended for use as a tool to define arbitrary regions within the 3D space defined by a grey-level voxel image. The painting actions are all undertaken using the screen pointing device which is typically a mouse or trackball. For drawing accurately this can be difficult and many users find it more natural to use a pen like device for drawing. The simplets device for this is a graphics tablet and therefore the possibility of using a tablet has been included. For this purpose support for the WACOM UltraPad tablet has been programmed in, specifically with code for the cordless pen and 4-button puck.

The tablet can be used in two ways. The first is an alternative input to control the screen cursor. In this mode the pen or puck can be used as a simple alternative to using the computer mouse and the benefit is that drawing with a pen is often more natural and easier to control for detailed positioning. The user is still required to look at the screen to define the domain. To use the system in this mode the sofware that comes with the tablet for the host machine is installed as per the instructions and no modifications are required in MAPaint (in this mode,so far as the program is concerned, user-events generated by the tablet are indistinguishable from that of the computer mouse).

In the second mode of use, printed images of each section are generated and the user draws with the tablet pen or puck directly on the sheet. The tablet coordinates generated by this action are then converted directly to voxel coordinates and thereby to define the domain. For this mechanism the tablet coordinates are read directly by MAPaint and converted using the coordinate mapping defined by the tablet reference points set in the tool controls dialog. The tool controls points are the coordinates in the reference image of two points that will be input from the tablet. Typically these will correspond to some fiducial point printed with the image on the sheet but could also be fiducial markers embedded with the embryo and stained to be visible.