Manipulating Shapefile data in FileMaker

[Seldom]

Great looking map.  I assume the green polygons are some sort of land cover, wooded areas, etc.

Are you getting that from USGS data or is it vectorized in New Jersey?

[Boyd]

Thanks. The data comes from the New Jersey Dept of Environment Protection (NJDEP): http://www.state.nj.us/dep/gis/lulc07cshp.html They have done a really nice job on this dataset, which just became available a few months ago. The previous version dates back to 2002, then I there's also a 1995 version.

The data is classified with the Anderson Code system where a four digit number represents a very specific type of landcover, such as "mixed forest with coniferous prevalent and 10-50% crown closure". See: http://www.state.nj.us/dep/gis/digidownload/metadata/lulc07/anderson2007.html

So the challenge is to distill all these codes into a manageable number of Garmin custom types, then create bitmaps to give the "flavor" of what they might look like. This is limited by Garmin's capacity for only two colors and bitmap size of 32x32.

I believe the NJ landcover is 48k - it looks pretty nice. I think it was traced by people from aerial photography - big job there! I guess this is the advantage of living in one of the smallest and most populated states - it is really thorougly mapped!

I would love to find some kind of high resolution landcover data for NY, PA, DE and MD since my map also covers portions of these states. Have not looked since last year, but at that time all I could find was the USGS 250k DLG landcover data.

[Boyd]

Took the map out for a road test today, and I continue to be impressed with they way the 3790 renders 3d in realtime. I would really like to see Garmin introduce a rugged version of this hardware with some more advanced menus. That would really blow away everything else on the market IMO.

[Hillbilly61]

I know this thread is old, but for posterity purposes the following is being thrown out there from the been there/suffered through it department:

* The shapefile format is really a relational database, with the primary relations being between the .dbf (data) and .shp (geometry) file. You can add columns to your heart's content to the .dbf file with an outside editor. This doesn't affect anything. Just save the .dbf as its original name and the shapefile will be "none the wiser."

* DO NOT delete or insert rows in the .dbf file. Doing so will screw up the relationship between the records and the geometry. If the shapefile loads at all, very strange results can be had.

* In terms of using a .dbf editor to modify the .dbf in a shapefile make sure it is dBase III compliant, as the shapefile really uses a dBase .dbf file. The reason for saying this is that some dBase file editors natively save to a dBase IV format. One of the big differences between the two is that a dBase III file does not support null values. Missing or omitted ASCII and numeric data is represented as a blank or a zero in a dBaseIII file. Nulls will make third party readers that closely implement this standard puke if they closely implement the shapefile spec.

[Boyd]

Good to know, although I pretty much learned all of this the hard way myself. I finished my first big project using the technique I described above, although I refined it a bit. Filemaker really handles this like a champ. Once I setup the database to import/export as I wanted, it only took about 4 clicks to process huge files.

The end result can be seen here: http://www.gpsfiledepot.com/maps/view/441/

That map has about 900,000 polygons representing landcover (not counting all the other map elements). I am now processing the data differently to make a new map, and created on big file that has all the polygons in it. I then exported it as a shapefile and did the processing on the .dbf file in FileMaker Pro. It had no problem ingesting all 900,000 records and spewing the modified ones back out. Took a few minutes to churn through it, but it worked great. I then opened the modified shapfile in Globalmapper and was able to make further modifications.

So, for the things I'm interested in doing, converting my vector data to shapefiles is a great way to automate my work and process large quantities of data with FileMaker. I even used to to process raster data by first converting it to vector format with Mapwel: http://forums.gpsfiledepot.com/index.php/topic,1693.0.html