15
votes
2answers
4k views

How can I convert data in the form of lat, lon, value into a raster file using R?

I have a data set of values over a km grid in the continental U.S. The columns are "latitude", "longitude", and "observation", e.g.: "lat" "lon" "yield" 25.567 -120.347 3.6 25.832 ...
9
votes
2answers
1k 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 ...
8
votes
2answers
2k 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 ...
8
votes
3answers
2k views

Ordnance Survey grids - download or generate?

Does anyone know a source from which to download vector UK Ordnance Survey grids at varying resolutions? Or failing that, a tool that can create an OS grid at a specified resolution? There are plenty ...
7
votes
1answer
1k views

Sort layers in QGIS table of contents?

When I load a bunch of layers into QGIS from PostGIS, they seem to load in reverse alphabetical order. Is there any tools or plugins that allow you to quickly sort the QGIS TOC in a different order? ...
6
votes
1answer
969 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, ...
5
votes
3answers
2k views

Is it possible to have a dynamic table in a data driven page environment?

I am creating a map series that has many polygons per sheet. There is annotation for the polygons however some polygons are very small with no annotation for them (annotation would completely hide a ...
5
votes
3answers
6k views

How to convert coverage (.adf) to shapefile?

Is there any tool or software except ArcGIS which I can use for converting coverage (.adf) files to shapefiles?
15
votes
3answers
22k views

How to merge multiple layers to one layer using QGIS?

I've imported several shapefiles which where exported from an Mapinfo .tab. Several tab files are imported resulting in 20+ layers. Afterwards I want to export it to geoJSON; but I'm reluctant for ...
6
votes
3answers
2k views

How to read Greek fonts (ISO-8859-7) in shapefile attributes within QGIS 1.8.0?

I'd like to ask whether there is a way to read greek fonts in a shapefile's attribute table within QGIS 1.8.0.
6
votes
1answer
4k views

How to add automate values to attribute field?

I have parcel, Buildings layers, without any information attribute table, and i want to replace "NULL" values with numbers form 1 to 2000, in "Parcel ID", or "Building ID" field thank you.
5
votes
5answers
2k views

How to calculate distances in a point sequence?

I'm looking for help calculating the distance between a sequence of points that are in a single Shapefile in QGIS. Below is what my data look like and a blank distance column I've added to show how ...
5
votes
3answers
6k views

Remove spatially duplicate features using ModelBuilder

I am creating a model to remove features which are duplicated within a polygon feature class. Most of the features are duplicated once, but about a quarter have up to three or four exact copies. I do ...
5
votes
2answers
4k views

Rotating a vector layer in QGIS with qgsAffine (or other method)?

I would like to rotate a set of vector points in QGIS an arbitrary number of degrees around a central point (or arbitrary point). This is similar to a recent question about creating a regular grid; ...
8
votes
3answers
828 views

When do I need to use a proxy with OpenLayers?

When exactly do I need to use a proxy with openlayers? I've done a lot of reading on this but can't seem to find a difinitive answer. Wondering if this is the route of my problems. For instance, if I ...
7
votes
3answers
1k views

How to interpret GRASS v.kernel results?

GRASS manual reads: v.kernel - Generates a raster density map from vector points data using a moving 2D isotropic Gaussian kernel ... Ok, but how do I interpret the results? I understand that ...
6
votes
3answers
5k views

Programmatically start and stop map services with Python

Is it possible to programmatically stop and start ArcGIS Server map services using Python?
6
votes
4answers
6k 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 ...
5
votes
2answers
692 views

Identify the latitudinal and longitudinal point directly beneath an object in space

Given the azimuth and altitude / latitude and longitude from the observer to the satellite, how can I accurately find the latitude and longitude of the point of intersection directly under the ...
4
votes
2answers
3k views

How to Partition Line into Segments using ArcGIS for Desktop?

I have a shapefile of U.S. states. I extracted the boundary between two states, resulting in a line segment. For example, the boundary between Georgia and North Carolina. Is there a way to further ...
3
votes
2answers
1k views

ArcObjects + comtypes at 10.1

Has anyone played around with using ArcObjects in Python at version 10.1? I am having all sorts of problems, such as TypeErrors when wrapping the ESRI OLB modules and AttributeErrors when attempting ...
3
votes
2answers
5k views

How to Extract by Attribute Using ModelBuilder with User Input?

Using ModelBuilder, I want to create a tool that will let a user choose the value or values that will be used to extract a shapefile. I have a parcel layer with a "Parcel_Type" field. I want the user ...
2
votes
1answer
1k views

How to avoid duplicate labels on each tile?

When I display my map using tiles a label gets drawn on each tile - is there any way to avoid this? I have attached an example image to show the problem:
7
votes
2answers
960 views

How to Refresh open attribute table in ArcMap using ArcPy rather than ArcObjects?

I am running the Calculate Field GP tool from the arcpy in ArcMap. When a row value is updated, it does not show up untill I use the Reload Cache tool (Table Options > Reload Cache). How do I refresh ...
7
votes
1answer
4k views

Understanding QGIS buffer tool units?

I have been trying to figure this out for a couple weeks now and have had no luck getting the buffer tool to accept anything but degrees as units of measure. I have found lots of stuff saying the ...
2
votes
2answers
461 views

Iterate through multiple Raster files and compute statistics using Zonal Statistics

I have a large number of raster images. What I'd like to do is to compute statistics on different sections of these raster files using a polygon. I think everyone is suggesting Zonal statistics. ...
37
votes
4answers
2k views

What are the FOSS equivalents to these ArcGIS products?

I'm a long-term user of ESRI software, and I now have a need to use free and open source software. I've been reading about Open Layers, PostgreSQL, PostGIS, GeoServer and MapServer but I can't find ...
32
votes
6answers
7k views

Downloading OpenStreetMap Data

Is there a straightforward way to download data from OpenStreetMap (OSM)? Using North America as an example, I realize Cloudmade (http://downloads.cloudmade.com/north_america) and geofabrik ...
24
votes
3answers
6k views

Alternatives to ArcGIS Online?

I am considering purchasing ArcGIS Online for a group of users who currently use about 5% of ArcGIS capabilities (ArcMap, simple map creation and information display) about 80% of the time. Primary ...
25
votes
5answers
45k views

What are Raster and Vector data in GIS and when to use?

What are raster and vector data in the GIS context? In general terms what applications, processes, or analysis are each suited for? (And not suited for!) In answering someone's question today, I ...
17
votes
6answers
6k views

Ways to Speed Up Python Scripts Running As ArcGIS Tools

This is a pretty general question. I just wondering what tips and tricks GIS programmers have used to speed up arcpy scripts that you import into the toolbox and run. I work most everyday writing ...
26
votes
4answers
6k views

How to find the minimum-area-rectangle for given points?

The following is another problem that I am working on it these days. As you see in the figure, (BTW, I tried to make it self-presenter) the question is: How to find the minimum-area-rectangle (MAR) ...
19
votes
2answers
9k views

How to convert ArcGIS .mxd file to QGIS .qgs file?

I recently tried to use QGIS and I wondered if you can convert a draft ArcGIS map (*.mxd file) into a QGIS project (*.qgs file). This would avoid thematize the entire project.
19
votes
1answer
4k views

Is WGS84 itself a Coordinate Reference System?

I was wondering the difference between WGS84 and EPSG:4326 (see this). Can then WGS84 on its own be defined as a Coordinate Reference System? Or is it just a datum so that a Coordinate System must ...
15
votes
6answers
11k 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 ...
31
votes
4answers
5k views

What are the pros and cons of PostGIS geography and geometry types?

My company uses geometry (the_geom) data type for storing geospatial data. I've recently been acquainted to the concept of geography (the_geog) data type which, as I understand it, stores the SRID ...
21
votes
5answers
11k views

Is ArcSDE no longer needed at ArcGIS 10.1?

Through my frustration of not finding the post-installation wizard with ArcSDE 10.1 and being unsuccessful with the command line tool to start an SDE service on our SDE databases, I found I was able ...
17
votes
3answers
4k views

How to put GeoServer layers behind authentication?

I want to publish map layers using OpenLayers and GeoServer. While this is easy enough to set up, I'm a bit lost when it comes to authentication possibilities. What I want is to create different users ...
16
votes
8answers
4k views

Versioning with ArcSDE - Is it possible to cancel or reject edits once they've been posted?

I am using ArcGIS 9.3.1 and attempting to work with an SDE geodatabase (with one polygon feature class) that has already been registered as versioned. I'm new to versioning and am still trying to ...
14
votes
4answers
6k views

How to add an attribute field to an existing Shapefile via Python

I have a Python script that adds an attribute field to a Shapefile if doesn't exist. This is easy to do with ArcGIS (graphically or via Python), but I'm looking for something that doesn't depend on ...
13
votes
3answers
4k views

Converting SimpleGeo Places GeoJSON file to shapefile?

SimpleGeo has recently made their "Places" data set freely available which is GREAT, because now we can use it for our own purposes, even offline. So I went about downloading the 2GB dataset, which ...
17
votes
4answers
9k views

How do I load OSM vector data in QGIS 2.x?

In QGIS 1.8 I used the openstreetmap plugin to request data from the server, or open a .osm XML file, which produced 3 layers (polygons, polylines and points) in QGIS. This was great (give or take the ...
13
votes
4answers
14k views

How do you decide what interpolation method to use for resampling raster data?

The question pretty much says it all; are there hard and fast rules about which interpolation methods are suited to each kind of raster data? Any Golden rules, rules of thumb? Good books or articles ...
12
votes
3answers
4k views

How to join attributes from nearest point in QGIS?

I have two layers with points, call them A and B, each with different attributes. For each point in A I want to join all the attributes from the nearest point in B. Ideally this would also include ...
25
votes
4answers
11k views

Which character encoding is used by the DBF file in shapefiles?

Which character-encoding is used by the dbf-file in Shape-files? It seems it is handled different, based on the program and the local encoding-settings of the machine. Which encoding is 'right' - ...
22
votes
6answers
921 views

What tools for regionalization/redistricting can you recommend?

I am looking for tools for regionalization / districting in GIS. So far I have been able to identify Districting ArcGIS extension (now also online) REDCAP (currently limited to 50k input polygons) ...
19
votes
4answers
6k 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 ...
19
votes
9answers
3k views

Are there any Indoor GIS platforms?

What sort of infrastructure is needed to allow me to write a simple mobile app for indoor navigation? Professor Mike Goodchild said: the average American only spends 13 percent of the time ...
17
votes
3answers
3k views

How can I switch line direction in QGIS?

Something that is hopefully pretty easy. I would like to be able to swap the direction of a polyline/line in QGIS. I made a custom tool to do this in MapInfo a couple of years ago, however I can't ...
11
votes
6answers
4k views

ESRI ArcMap Add-in with app.settings not recognizing app.config changes

I have an ESRI Add-in developed for ArcMap which requires a configuration file. After spending a while trying to read config values from a single App.Config file (and always getting null) I believe ...

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