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Optimizing GPS accuracy

Optimizing GPS accuracy. Bence Sprok 16/08/2009 - Miskolc. Why and when shall we use GPS?. - Shall not be used for sprint maps - Useful when no base map is available - Or only aerial photo is present - Early phase – creating base map, polygons

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Optimizing GPS accuracy

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  1. Optimizing GPS accuracy Bence Sprok 16/08/2009 - Miskolc

  2. Why and when shall we use GPS? - Shall not be used for sprint maps - Useful when no base map is available - Or only aerial photo is present - Early phase – creating base map, polygons - Might not be fast for later processes

  3. What kind of unit? - “Hobby” type will be fine - We don't need professional units (cost 5000 €<) - At least 2, but preferably 3-4 different ones - High sensitive receiver (SiRF III< , MTK, etc.) - External antenna is highly recommended - Forget the “built-in” types (Forerunner and others) and the car navigation systems - Look for the trackpoint memory

  4. ~350 € ~20 € ~60 € ~60 € ~60 €

  5. How to use? - All GPS work simultaneously - Use distance based recording (~3m) instead of time interval, if possible. - Along with the “analog” accessories (board, pen, notes) - Try to keep them as high as possible (special cap, backpack) - Try to plan your work according to the satellites' positions - One track is not a track. Try to track main features more than once in different time period. - Use waypoints

  6. - Download your work with your favourite program - Edit it - erase unnecessary parts - Filter it if you used time interval method - Convert it to .gpx format If needed, use gpsbabel to do that - Transform from WGS'84 to the desired projection My suggestion is GlobalMapper

  7. Why do we need GlobalMapper if OCAD is present? - GlobalMapper supports any kind of projection (OCAD supports only the most commonly used) - Watch for the map datum and projection (according to your source) - Bearing must not distort (it's a must for any kind of topographic map)

  8. Magnetic declination - Orienteering maps represent magnetic North - Calculate the declination online http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp

  9. Advantages - Disadvantages +Saving time + Better accuracy in certain cases + Reference aerial photos (GM/OCAD) + Combine mapmakers’s work - Pine forest, deep valleys - Height (z-level) data - More work for preparing - Costs?

  10. Questions?

  11. Wake up! Lunch time!

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