From d5f8c6cb6e5156e1e6ee29cf9c86f58db5a540a7 Mon Sep 17 00:00:00 2001 From: Daniel Schadt Date: Tue, 7 Mar 2023 19:19:40 +0100 Subject: add some documentation about transformers --- doc/user/transformers.rst | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 doc/user/transformers.rst (limited to 'doc/user/transformers.rst') diff --git a/doc/user/transformers.rst b/doc/user/transformers.rst new file mode 100644 index 0000000..c8ddf01 --- /dev/null +++ b/doc/user/transformers.rst @@ -0,0 +1,45 @@ +Transformers +============ + +Transformers are small (or big) transformations that are applied to your GPX +track after it has been uploaded. This allows Fietsboek to provide some common, +simple editing options, without users having to do that themselves. + +All transformers are optional and disabled by default. You can enable +transformers when uploading a track on the bottom of the page. You can also +enable transformers for already uploaded tracks in the editing view. + +.. note:: + + When enabling transformers for already existing tracks, your browser might + not show the changed track. Try force-refreshing (Crtl + F5) the page so + that it reloads the GPX from the server. + +In other applications, transformers are sometimes called "filters". That term +however has many different meanings (like the filters on the "Browse" page), +and as such, Fietsboek calls them transformers. + +Fix Null Elevation +------------------ + +The *fix null elevation* transformer removes points at the start and end of a +track that have a "wrong" elevation. This helps to avoid issues when GPX +trackers don't have elevation data yet and fill in 0, leading to wrong uphill +calculations and wrong diagrams: + +.. image:: images/wrong_elevation.png + :width: 200 + :alt: An elevation graph that starts at 0 and makes a jump to 165. + +Activating the transformer will produce the following track: + +.. image:: images/fixed_elevation.png + :width: 200 + :alt: The same track, but with a fixed elevation graph that starts at 165. + +The transformer considers "wrong" elevation to be either points that have an +elevation of 0, or points that have a slope of more than 100% to the next +point. + +To fix those points, the transformer will find the first correct point, and +copy its elevation to the wrong points. -- cgit v1.2.3