Tagged Questions
0
votes
1answer
24 views
Convert Mapnik TMS python script from EPSG:4326 to 3857
May I ask help from this group to convert this Mapnik 2.1 python script from EPSG 4326 to 3857? I am not enough familiar with projections, and I am missing some points somewhere... Particularly, Im ...
0
votes
0answers
93 views
How to re-project the EASE (Equal Area Scalable Earth) grid with a ~25 km cylindrical projection to WGS84 0.25 degree?
I have nc files ,here is one file https://echange-fichiers.inra.fr/get?k=LUfqiyO1Dl7az5bihnS. from the metadata ,the projection is cylindrical and the resolution is 25 km:
...
2
votes
0answers
83 views
projection discrepancy with gdal (1.9) and proj4
I boiled the problem down to that python example:
import sys
try:
from osgeo import gdal
from osgeo import osr
except:
import gdal
import osr
if __name__ == '__main__':
version_num = ...
1
vote
1answer
632 views
Mapping x, y pixel coordinates to latitude and longitudes on the WGS84 datum
Apologies in advance for the long question, I am fairly confused at this point and I figure if I show my thought process any flaws early on in the piece can be more easily pointed out.
I have a grid ...
6
votes
1answer
600 views
Python script to convert Lat Long to ITM (Irish Transverse Mercator)
I am currently working on a python script that converts Lat Long (WGS84) to ITM. The formulas used are based on a paper published by OSGB (Appendix B):
...
3
votes
1answer
305 views
Calculate bounding box + buffer for rendering a map tile with mapnik library
Mapnik library has a Projection object (I'm using Python bindings):
spherical_mercator = '+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null ...
0
votes
0answers
66 views
How can I convert a Winkel Tripel map to a Mercator map?
I have a map of the world (a PNG file) which uses Winkel Tripel. I'd like to convert it to Mercator. I would just use pyproj, but it lacks an inverse "wintri" projection.
5
votes
3answers
640 views
Using arcpy what is the most efficient way of projecting a selection from a large data set?
I have a large data set X(x1-xn) from which I must select consecutively the attributes A(a1-an) from X.fieldsSRC or X.fieldDST and project the selections.
I have a functioning arcpy script that does ...
1
vote
1answer
172 views
Defining multiple projections inside a file gdb [error 000289 failed to alter spatial reference]
I am importing multiple shapefiles into a filegdb in ArcGIS 10, and using the following code to define the projection of the feature once imported, to the .prj of the original .shp file.
Here is my ...
4
votes
4answers
1k views
Automate Projection of multiple shp files using ArcPy
I have been trying to create a Python script that will convert all shape files within a folder from GCS WGS 84 to Web Mercator. Below is the code I have so far but what I'm struggling with is how to ...
2
votes
1answer
335 views
How to determine area of pixel in meters with GDAL and Python?
I have a raster loaded in Python using GDAL bindings. I'd like to be able to determine the area of a pixel in meters although I'm not confident that the projection is in meters. On this page I see a ...
7
votes
2answers
2k views
Measuring distance in spherical Mercator vs zoned UTM
I've got points in WGS84 lat/long and I'd like to measure "small" (less than say 5km) distances between them.
I can use the haversine formula from http://www.movable-type.co.uk/scripts/latlong.html ...
15
votes
6answers
9k views
How can I define projections for multiple shape files in ArcMap 10 at once?
I have over 100 shape files that don't have .prj file and thus when I bring them into ArcMap they show the coordinate system as unknown. I know all of the shape files coordinate system is GCS WGS ...
