Topics

Is it possible to make custom tidepoints that will work like the US tidepoints that come with either the Garmin basemap or the GPSMATE 168 Sounder Tidepoint maps? I tried searching for this here and also using google, but didn't find an answer.

Hello, I came across this forum in my search for guidance. First, I consider myself a total newbie at this stuff so bear with any mistakes I have made. I have found that my local government has published GIS data of our region including files of trails. This data is available in several formats including SHP, FGDB, Autocad, and KMZ. I wanted to eventually turn this data into a layered map for my GPS, but I am a long way from that and am just going to concentrate on getting a good GPX file for now.

After searching on how to handle these formats, I have discovered that I am further disadvantaged in that I use a Mac which seems to be lacking in GIS tools. I have managed to unzip the KMZ into KML data and then ran that dataset through gpsbabel with a simplify filter to decrease a bit of the extraneous trackpoints. This resulted in a GPX file with almost 3200 tracks. Unfortunately, the dataset is messy in that often many tracks are used for one trail, making the xml code bloated and slow - the GPX file is almost 80mb and contains about two million lines of xml code. I managed to clean out all the <ele>0.0000000</ele> lines of code to trim the xml file down to 52mb and 1.3 million lines of code, but that is still very bloated.

At this point, I have basically started to manually examine the tracks for each trail or set of trails to try and combine tracks into trails and clean up the code. So far I have cleaned 70K lines of track code, but looking at this project, this looks like it will take a long time if I continue down this route.

I was wondering if anyone has a better workflow or suggestions that I would be able to use. If anyone is interested in the original source of data, it can be found here:

metadata info page: http://www.geoweb.dnv.org/data/metadata.php?dataset=TrnTrailPublic

The "TrnTrailPublic" datasets can be found on this page: http://www.geoweb.dnv.org/data/
almost at the bottom (alphabetically listed datasets) under Trails.

Thanks for any thoughts or help.