14
votes
1answer
497 views
What is the most accurate coordinate system for calculating areas of polygons?
I have multiple polygons, all located offshore around the UK. I am trying to calculate the areas of these polygons in square kilometres, without splitting them by UTM zone.
Is it possible to do this ...
8
votes
3answers
1k views
How to emulate Google Maps driving directions using pgRouting?
Would like to emulate google maps' driving directions functionality but use pgRouting instead. google's data over the project area & scale is quite a bit off so we want to use our own transport ...
13
votes
1answer
2k views
How to define new custom projections in QGIS?
I'm trying to define a projection in QGIS. I want to add North America Albers Equal Area Conic. From the spatialreference site I copied the proj4 line:
+proj=aea +lat_1=20 +lat_2=60 +lat_0=40 ...
13
votes
4answers
821 views
algorithm to place maximum number of points within constrained area at a minimum spacing
I have a polygon layer that describes a constraint; I wish to add points within this area. I want to add as many points as possible, but they must have a minimum spacing between them. Is it possible ...
8
votes
2answers
3k views
How to perform Raster Reclassification in QGIS?
Is there a way to do reclassify a raster image to Qgis?
In Arcgis you can do that in Spatial analyst Tools-->Reclass-->Reclassify
Any ideas?
4
votes
3answers
1k views
How do I include a variable in the where clause of arcpy.Select_analysis?
I am trying to loop through a shapefile, selecting each feature in turn and copying it to a temporary shapefile to by included in a union analysis. I'm using a cursor to find the ID name for each ...
5
votes
1answer
415 views
Qgis polygonize problem - DLL load fail
I have a raster file and I want to perform the method "polygonize". Then the problem occurs, that is shown on the screenshot.
It doesn t have anything to do with the rasterfile format, I veryfied.
...
29
votes
7answers
4k views
How can I effectively debug arcpy Python scripts?
I have written many Python scripts using arcpy in ArcGIS 10, and so far my only means of debugging is restricted to printing messages to the geoprocessing results window using arcpy.AddMessage(). Are ...
48
votes
19answers
34k views
How can I convert between KML and ESRI's shapefile format?
My users are sending me point data that were digitized using GoogleEarth. How can I convert their KML to a shapefile?
19
votes
4answers
1k views
Curved point-to-point “route maps”
I have recently been looking at airlines web pages that display their routes departing a certain city to all other cities they service. I would like to be able to create similar curved routes between ...
16
votes
3answers
749 views
Best practices for organization and tidiness - How do you deal with multiple copies of layers?
Back in the days when I was in the university I had a "Organization and tidiness" problem – I was unorganized and kept my layers in different folders without distinct names and hence had multiple ...
22
votes
9answers
9k views
How can I connect to a PostGIS database from ArcMap 9.3 and 10.0?
How can I connect to a PostGIS database from ArcMap 9.3 or 10.0?
Ideally, I would like to be able to perform spatially enabled queries and receive the results back (e.g. spatial and non-spatial ...
19
votes
7answers
9k views
Removing small spaces between polygons
I have a set of polygons representing administrative districts. The districts were digitized by hand, and there are small spaces between polygons where the polygons should be touching. How can I ...
16
votes
3answers
847 views
Packing Polygons within polygon
I have a Boolean raster.
In the grey areas of the raster I would like to fit a given size polygon within a contiguous extent.
Basically, I have an irregular polygon, and i would like to "fit" a ...
11
votes
8answers
5k views
How can I convert an excel file with x, y columns to a shapefile?
How can I convert an excel file with x, y columns to a point shapefile?
There are some somewhat optional requirements in addition to the correct creation of a shapefile:
Column types (as per ...
10
votes
3answers
4k views
list all feature classes in GDB, including within feature datasets
From python how can I build a list of all feature classes in a geodatabase, including inside feature datasets? The standard example only lists FC's at the top level of the gdb:
import ...
8
votes
5answers
3k views
How to convert ArcGIS Server JSON to GeoJSON?
I'm creating a web map using Leaflet, and I want to be able to grab feature layers from our ArcServer. I have successfully been able to retrieve a feature class as JSON, but Esri's JSON objects don't ...
8
votes
3answers
5k views
How to change feature class and field aliases in bulk?
I have over a hundred FCs, each with 10 or 20 attributes to add or change the aliases for, two or more times a year. Needless to say, this is not something I'm going to grunt my way through. How can I ...
10
votes
2answers
8k views
How to calculate polygon areas in QGIS?
Hi I would like to simply calculate areas of a area-shape file in square meters or in acres (ha).
I didn't find that functionality in the vector tools.
Could anyone here help me with that?
6
votes
1answer
736 views
Nearest Neighbor calculation in PostGIS
I'm learning how to use PostGIS and spatial databases for analysis. What I am trying to do is perform a calculation to get the distance for the nearest polygon in a file, using the edge calculation, ...
4
votes
4answers
1k views
How to split a vector in equal smaller parts in QGIS or similar?
i want to divide a shapefile with many tiles into a lot of smaller tiles.
I am searching for a smart solution, because manual edits are out of questions
Anyone can help or know a nice function?
6
votes
5answers
4k views
How to join multiple records to single feature?
apologies for what I'm guessing is a really easy problem to solve. GIS user, not programmer here.
I'm trying to create a join/relate in QGIS where I have a shapefile of buildings and to that I would ...
7
votes
2answers
1k views
Workflow for determining stream gradient?
As far as data goes, I'm working with NHD .shp files, 10m DEMs, and some LIDAR data.
My goal is to determine gradient for 100m segments of a network of streams.
I'm already able to do this, but I ...
4
votes
4answers
3k views
How to reproject base layers in OpenLayers?
The issue is:
I have vector/topo/image tiled maps for some places in north america which were published as ArcGIS Server REST service. These maps (A) are based in EPSG26912 projection. Now I wanna ...
6
votes
1answer
2k views
How to create a point along a line given distance
I have been given a non-spatial database which contains the names of lines which I have a shapefile for. The database also has names of points and the distance of each point from the origin along the ...
4
votes
2answers
1k views
Unable to create WFS successfully
I know there has been lots of WFS assistant and I did follow this one word by word, which I found was the best in the entire gis stack but still no clue why I am unbale to render a WFS on base map.
...
40
votes
19answers
4k views
What are some Free and Open Source GIS Desktop packages
Can someone please give me a list of free and open source GIS desktop packages?
30
votes
7answers
5k views
Creating drive time polygons using open source tools
Is anyone using open source tools and/or data to generate drive time polygons that radiate out from a given location? For example, I have used ESRI products like Network Analyst and Business Analyst ...
19
votes
2answers
2k views
Spatial ETL comparisons
I am hoping some of you experts out there can list the pro's and con's of various spatial ETL (extract, transform, load) tools. If you have used these items listed here (or add your own), please ...
19
votes
8answers
2k views
17
votes
4answers
1k views
How do GIS web apps work?
I am completely new to GIS and therefore have questions regarding how the GIS Web development should be made, because the entire concept still confuses me.
So, imagine I have a map. And by this, i ...
10
votes
3answers
537 views
How can I generate irregular grid containing minimum n points?
Given a large (~ 1 million) sample of unevenly distributed points - is it possible to generate irregular grid (in size, but could also be irregular in shape if that is possible?) that will contain ...
14
votes
9answers
3k views
Bulk Geocode 20 million records
Are there any free or reasonably priced databases for the US which can be searched and return latitude and longitude information?
9
votes
5answers
5k views
Is there an open source Geocoding tool which can be used commercially?
Is there any Geocoding tool which is open source and can be used in commercial application?
We tried Google geocoding API's but cannot continue with it because of some licensing limitation.
Now ...
19
votes
9answers
1k views
Discontinuous or Interrupted map projections?
Do any of the current open source GIS softwares support discontinous projection systems? E.g. sinusoidal, dymaxion, butterfly, etc? If not, are there any affordable commercial ones that do (affordable ...
8
votes
2answers
252 views
Create a summary table of the symbology of all datasets in multiple mxd's
This is related to the following Retain ESRI symbology in Mapinfo TAB . As an initial step (in arcpy) I want to access the symbology of all the datasets and create a document which has the details of ...
8
votes
3answers
2k views
Land Cover Feature Extraction from Satellite Imagery
I'm interested in a low-cost or open source solution for creating land cover GIS layers that utilize both spectral and textural extraction algorithms. I have used PCI Geomatica, ENVI, and Feature ...
15
votes
4answers
3k views
Maximum number of point features in an OpenLayers vector layer
In your experience, how many point features can be added to an OpenLayers vector layer (new OpenLayers.Layer.Vector("Point Layer")) before it goes unusably slow?
My use case is to display points from ...
16
votes
7answers
1k views
GIS data for fast food industry
I am working a small project related to fast food industry. I am trying find GIS data for fast food chains like subway, MC Donald's, Arby's, etc in state of Ohio. Basically, I am looking for point ...
14
votes
3answers
2k views
How do I find the distance between two coordinates in an ellipsoid?
Lets say I have two sets of latitude and longitude. How do I find the distance between the two locations if I assume the earth is a perfect ellipsoid (with an eccentricity of 0.0167)?
13
votes
5answers
565 views
How to make a GIS inventory?
My office will be seeing a big change in its GIS section. This section has been operational since the 1980's and has a huge collection of GIS data (i.e., shapefiles, raster files, data, etc) but never ...
6
votes
2answers
2k views
How to convert Distance, Azimuth, Dip to XYZ?
I have an excel spreadsheet with header and survey drill data. Header data contains hole ID, and location coordinates, and the survey data contains related downhole survey with Distance, Azimuth and ...
12
votes
5answers
4k views
How to get the extent of each polygon in a shapefile?
In arcgis 10 and python I want to get the extent (xmax, ymax, xmin, ymin) info of each of the polygons in a shape file.
I can get the extent of the whole shape file using
...
8
votes
2answers
686 views
How can I convert geomagnetic coordinates to geographic coordinates without doing the math myself?
I have some data which are in geomagnetic coordinates; that is, they are latitude and longitude, but in reference to the magnetic north pole in Canada rather than the geographic north pole. As you ...
5
votes
3answers
4k views
Define Workspace for SDE Connection in Python
How do we define SDE Connection for workspace in Python Scripting. Its urgent please need your suggestion. Thanks
7
votes
2answers
485 views
Elevation profile 10 km each side of a line
How can I get an elevation profile for a band of terrain?
The highest elevation within 10 km (on each side of the defined line) should be taken into account.
I hope my question is clear.
Thank you ...
7
votes
3answers
3k views
Tutorials for geoserver
Do you know any sources from where i can learn how to use geoserver?
I know this two sites:
http://geoserver.org/ - which in fact is not working (at list at the moment)
...
6
votes
1answer
632 views
Difference between Geographic-3D and Geocentric CRS
I'll start with the OGP definitions:
Geographic. A coordinate reference system based on a geodetic datum and using an ellipsoidal (including spherical) model of the Earth. This provides an accurate ...
6
votes
3answers
3k views
Programmatically start and stop map services with Python
Is it possible to programmatically stop and start ArcGIS Server map services using Python?
5
votes
6answers
2k views
How to get “.GDB” Esri File Geodatabase in QGIS for MAC OSX 10.6?
I understand there are programs like OSGeo4W that allow windows users to work with File Geodatabases, but is there something similar for Mac OSX?
