1. Timestamp as M-value on SpatiaLite + QGIS

    Feb. 24, 2019 | tags: GPS

    After spending weeks playing with my own 2-year GPS log, I wanted to colorize each track gradiently based on velocity.

    While it sounds straight-forward to use the "trackpoints" table in the same SpatiaLite database to achieve this, it turned out not so. Plotting millions of points is quite slow and …

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  2. GPX Editor Comparison for Manual Cleansing

    Feb. 10, 2019 | tags: GPS

    Summary

    GPS tracks have to be cleansed (removing outliers) before analysis, and cleansing requires some manual editing.

    For this manual editing, I searched around for a good tool. Many are available, but there's no definite winner. Here's the detailed comparison.

    Note that this comparison is only for manual cleansing of …

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  3. Smoothly Browsing 2-year GPS Log on Map

    Jan. 31, 2019 | tags: GPS

    I recorded GPS log almost everyday over 2 years from 2005 to 2007. The total size of the log is about 1GB in more than 1,000 NMEA files. There are several millions of track points.

    These numbers have been challenging for browsing all log at once on a map …

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