Warping

Landmark warping

Step 1: Define template landmarks

  • Add landmark: Left-click outside template

  • Delete landmark: Right-click on a landmark

  • Move landmark: Left-click and drag landmark

  • Finish: L to lock template (Points cannot be added after locking template!)

Step 2: Adjust source templates

  • Move landmarks to homologous locations on each source

  • Select source: left-click on line OR use arrow keys to cycle through sources OR click on relevant row from the table

  • Move landmark: Left-click and drag landmark

Manual warping

Manual (Gaussian-kernel-based) warps are defined using four parameters:

  • y — original 1D data

  • center — warp kernel center, relative to its feasible range (between 0 and 1)

  • amp — warp kernel amplitude, relative to its feasible range (between -1 and 1)

  • head — warp kernel head width, relative to its feasible range (between 0 and 1)

  • tail — warp kernel tail width, relative to its feasible range (between 0 and 1)

The meaning of these four parameters is depicted in the figure below.

(Source code, png, hires.png, pdf)

../_images/warping-1.png

In order to conduct manual warping, follow the steps below.

See also the manual warping screencast.

Step 1: Position the mouse

  • Move the mouse on the axes to the position at which you wish to initiate the warp. This will set the center parameter.

Step 2: Initiate the warp

  • Press the “W” key to initiate a manual warp.

Step 3: Adjust the warp

  • Drag the mouse left-and-right to adjust the amp parameter.

  • Drag the mouse up-and-down to adjust the head and tail parameters.

Step 4: Finalize the warp

  • Press “Enter” to apply the warp. Alternatively press “ESC” to cancel the warp.

Step 5: Restore to original data

  • If you are unhappy with the warp results, press “R” to restore the original data.

  • This will delete all existing warps for the currently selected curve.

Restoring previous sessions

If something went wrong during warping (e.g. a software crash), or if you would like to revisit previous warping sessions, then:

  1. Launch mwarp1d

  2. Drag a previous session’s output (NPZ) file on to the main window’s Drop Data box.

This will restore the previous session, allowing you to adjust and/or reset the previously saved warps.