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I'm new to GIS - I have a background in statistics. I have the following proj4string:

'+proj=lcc +lat_1=40.66666666666666 +lat_2=41.03333333333333 +lat_0=40.16666666666666 +lon_0=-74 +x_0=300000 +y_0=0 +datum=NAD83 +units=us-ft +no_defs +ellps=GRS80 +towgs84=0,0,0'

Can someone explain:

  1. What the parameters mean (I think lcc means 'lambert conic conformal')
  2. Where I should go to learn how this works/what projections are available?
  3. The input lat, lon coordinates are in decimal degrees. What are the output units? The +units=us-ft suggests feet
  4. I want to focus my analyses on Manhattan, Brooklyn, Queens, the Bronx. As part of my analysis, I want to split my projected map into a grid. Ideally, each cell will be, say, 1/10th a mile square. What projection should I use for this sort of work? Is LCC acceptable?

closed as too broad by Midavalo Feb 13 '17 at 17:20

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • LCC is Lambert Conformal Conic, but close enough ;) – Erica Mar 19 '15 at 18:01
  • Answer on question #2 (where to find information on proj4strings): You may find some useful info here: proj4.org – Jelmer Feb 13 '17 at 16:42
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Please keep the site order to put only one question at a time.

https://trac.osgeo.org/proj/wiki/GenParms will show you what the Proj.4 parameters mean.

If you have input and output, you have to define projections on both sides. Changing the proj.4 definition does not change the coordinates automatically. Instead, you make simply 12 meters out of formerly 12 degrees. This is not what you intend.

For coordinates, use cs2cs, for vector data ogr2ogr, and for raster data gdalwarp.

Your 4th item should better be another question.

  • sorry I don't follow "If you have input and output, you have to define projections on both sides. Changing the proj.4 definition does not change the coordinates automatically. Instead, you make simply 12 meters out of formerly 12 degrees" As I 'understand' it my proj4string lets me map coordinates in decimal degrees to some projection, which seems to have horizontal units in feet? Could you explain more fully please? – user3279453 Mar 19 '15 at 19:26
  • The string only says that map coordinates are us-feet. No word about decimal degrees coordinates. If you have degrees and want to get feet, you have to reproject your data using one of the three tools I mentioned. There you can say that the input source CRS is WGS84, NAD83 or NAD27 in degrees, and what you want as target CRS. – AndreJ Mar 19 '15 at 20:10

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