In dankelley/imager: Mouse-Based Image Digitizer

knitr::opts_chunk$set(collapse = TRUE, comment = "#>")

A sample screenshot is shown below. The purpose is to trace the outline of a schematic side-view of a Right Whale (Eubalaena glacialis), taken from Daoust et al. (2018). Since this diagram is drawn natural scale, just a single value was used to specify the $y$ coordinate). At this stage, 13 points have been digitized, and the mouse is hovering over $x=0.431$ and $y=0.114$.

Magenta lines and labels indicate the specified coordinate system, and dotted blue lines are a grid that (sometimes) can be useful in guiding the eye.

Any point clicked in error can be eliminated by clicking the Undo button, which removes the most recently added point. (Actually, Undo will remove all the points, if the user clicks enough, but it a good idea to keep a close eye on the digitized points, so that only single-point corrections will be required.)

Clicking the Save button saves the results to a file, and clicking the Code button shows how to read that file and plot the digitized points. (Note that clicking the Quit button saves the file first.)

Various GUI elements permit controlling the look of the digitized points. These can be helpful in digitizing graphs that have points on them. It is also worth nothing that open symbols can be a good choice, since they make it easier to check that the point was clicked appropriately.

References

Daoust, Pierre-Yves, Émilie L. Couture, Tonya Wimmer, and Laura Bourque. “Incident Report. North Atlantic Right Whale Mortality Event in the Gulf of St. Lawrence, 2017.” Canadian Wildlife Health Cooperative, Marine Animal Response Society, and Fisheries and Oceans Canada, 2018. https://publications.gc.ca/site/eng/9.850838/publication.html.

dankelley/imager documentation built on Aug. 7, 2021, 4:07 p.m.