8
votes
3answers
1k 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 ...
6
votes
4answers
6k views

Qgis - Is there a way to split a polygon layer with a line layer?

I am drawing administrative regions that have boundaries follow streets in another layer. As these streets are pretty long with many vertices, I don't want to re-trace them. I am looking for a way to ...
6
votes
3answers
6k 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 ...
5
votes
2answers
3k views

How to create multiline labels in QGIS?

How can I apply Multiline label option in the label property.Name field contains a lengthy name. I want to wrap it. How can I do it? please help me. My QGIS version is 1.8
5
votes
2answers
3k views

How to add links to PDFs in a Shapefile?

I have a problem. I want an attribute in a shape file named "Link" to add. The works are all fine. But then I would like to add a link in my directory. This link accesses a PDF. Now, this PDF is not ...
5
votes
1answer
835 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. ...
5
votes
2answers
7k views

How to sort a feature class and then calculate a sequential ID field?

I am in ArcMap and I want to sort the records based on a field and then do a Calculate Field with an auto-incrementing value with the sort in-place. Any ideas? It looks like I could get an update ...
4
votes
2answers
342 views

Summary table with a field that shows components of each summarized record

I have a table with 2 fields the first is for community and the second for the main community that it belongs to, as in the image I want to summarize the second field (Belongs_to) but with an extra ...
4
votes
2answers
12k views

Create polygon layer from polyline layer

Our systems expect polygon shapefiles, representing a collection of non-intersecting and geometrically valid (multi)polygons. Specifically, farm fields. We often receive our representations of farms ...
3
votes
5answers
2k views

How to vary the transparency of symbols within a single layer in ArcMap?

I have a polygon layer which I am drawing in ArcMap using a graduated color symbology: Is it possible to vary the transparency between the classes, so that the transparency tapers off with the ...
3
votes
4answers
2k views

Cannot fix QGIS after upgrade to Ubuntu 13.04 Raring

I have following problem. After upgrade to 13.04 I had problem with PyQGIS mentioned here. I followed almost all advices described there, finally removed QGIS (had 1.8 Lisboa) and added the Ubuntugis ...
3
votes
1answer
2k views

How do I find vector line bearing in QGIS or GRASS?

How can one extract the bearings from a set of lines in a vector file? I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...
2
votes
2answers
322 views

How can I access `processing` with Python?

I want to access the explode lines function in Python outside of QGIS from a standalone script. What module do I have to load in order to use it? How can I access processing? from qgis.core import * ...
7
votes
1answer
655 views

How to reopen hidden panels in print composer?

I unfortunately deleted the menu (Qgis 1.8.0) in print composer (settings for labels etc) . Now I am wondering how to display it again? The menu is gone in all my projects and I could not find a ...
4
votes
1answer
887 views

How to add Table to Layout View using ArcPy?

I am using ArcGIS 10.1 and I have a non-spatial table and some layers in a Data Frame. When I switch to Layout View I want to be able to show the map in a data frame element and the table in another ...
4
votes
3answers
25k views

How to fix Runtime Error R6034: An application has made an attempt to load th C runtime library incorrectly?

I just downloaded QGIS 2.0 and everytime I open it I get this error message window popping up: Does anyone know what this means or how I might be able to fix it? Thanks!
4
votes
3answers
4k views

Automatically update field value in one column based on change to another column in same table?

When editing I want to be able to change the attributes of one field and upon doing this allow for the automatic update of another field in the same attribute table. Essentially I have one layer ...
4
votes
3answers
2k 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. ...
3
votes
1answer
84 views

Why isn't the service layer shape properly spread out?

I created a simple service layer polygon in network analyst (ArcGIS Desktop 10.2) with no hierarchies set in the street network. Now I don't understand why is this polygon created along some ...
3
votes
2answers
1k views

Calculate line distances inside of polygons using ArcGIS for Desktop?

I'm working with two data sets: NHD polyline stream layer for my entire state HUC Watershed boundary Polygons for the entire state I am looking for a way to calculate the total length of streams ...
2
votes
1answer
1k views

How to evaluate raster calculator expressions from the console?

How can I execute from the console an expression that should be used with the raster calculator? I'm searching for something like this: qgis.someRasterCalcClass.evaluate("boh@1 + boh@2", ...
32
votes
9answers
13k views

Open source methods for kriging?

I have a point dataset which I'd like to Krige, ideally using an open-source software package. If possible, I'd also like to choose the semi-variogram model during the process to improve the ...
22
votes
3answers
2k 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 ...
41
votes
8answers
53k views

What is the difference between DEM, DSM and DTM?

I am listing some of the acronyms used in our work and had to stop to think about whether to list these together or separately. In some circles they are synonymous, in others they have distinct ...
33
votes
4answers
13k 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) ...
24
votes
9answers
3k views

Effectively displaying demographic data on a printed map

I would like to plot the following per zone (30 zones total) data on a printable/non interactive map: Average age Average household income Number of households Population density Number of people ...
21
votes
6answers
9k 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 ...
25
votes
4answers
7k views

How to smooth a DEM?

I have a SRTM DEM and I want to create a shaded relief from it. I created the shaded relief in GRASS and the result is very nice, but a little rough becouse the area is near flat and the DEM is 90m in ...
20
votes
1answer
6k 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 ...
11
votes
1answer
7k views

How do I calculate the latitude and longitude of points using QGIS?

I'm trying to figure out how to calculate the lat/long of points using the QGIS field calculator. Is there an easy way to do this? I saw a previous related question, but it deals with a more advanced ...
19
votes
5answers
5k 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
2answers
9k views

How to run a simple python script for QGIS from outside (e.g. Sublime Text)?

I would like to run a few small and simple python scripts for QGIS (Mac) from "outside" of QGIS. With outside I mean in this context, either the normal os command line (terminal.app) or even better, ...
12
votes
1answer
3k views

How to perform Random Forest land classification?

This is a follow-up to a previous post: Machine Learning Algorithms for Land Classification. It seems that the Random Forest (RF) classification method is gaining much momentum in the remote ...
21
votes
5answers
3k views

Is there a source for historical shapefiles and tiles? [on hold]

Is there a source for historical shapefiles and tiles? Like the ancient Greece/Rome, medieval Europe and Japan? Ideally with multiple snapshots during different periods in their development, since ...
20
votes
3answers
4k 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 ...
15
votes
4answers
6k 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 ...
19
votes
4answers
21k 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 ...
8
votes
1answer
5k views

Is there an comparison of the various mapping libraries for Android?

I am currently looking at the various libraries that I can use to show a map in my custom Android App. I have found several like Mapsforge, OSMDroid, ArcGIS runtime for Android, Google Maps for ...
35
votes
3answers
31k views

What is the difference between WGS84 and EPSG4326?

What is the difference between WGS 84 and EPSG 4326? It seems like for a given dataset it might be both WGS 84 and EPSG 4326.
16
votes
4answers
14k views

Creating Centrelines from Road Polygons/Casings?

I want to create center lines from road polygons. Are there any automated tools in ArcGIS for Desktop to do this? I am including a Screenshot of my vector file below.
14
votes
3answers
4k views

How to snap lines to points automatically?

I have two vector shapefiles: One file is points representing manholes and the other is a polyline file representing pipes leading to and from the manholes. I need to snap the lines within a ...
19
votes
9answers
5k 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
7answers
4k views

Creating trade flow maps in ArcGIS for Desktop (or any free software)?

I am trying to represent trade flows on a world map where the size and direction of arrows indicate the exports/imports of a given country. This type of map is commonly found in magazines and ...
15
votes
3answers
4k views

Visual Impact Assessment in QGIS or GRASS

Is it possible using QGIS or GRASS to perform a Zone of Visual Impact assessment? E.g. where can a 100m high structure be seen at a viewing height of 1.8m within 30km, taking into account elevation ...
13
votes
4answers
4k views

How to create one-sided buffers or parallel lines in PostGIS?

I'm looking for a way to create so-called one-sided buffers or parallel lines in PostGIS. Example: 1. buffer, 2. one-side, 3. both-sides I've found some discussion on the mailing list from 2009 and ...
12
votes
3answers
20k views

How to convert .shp to .csv including attributes AND geometry?

I have a .shp file with 60k+ entries, all of which are polygons with corresponding attributes (acreage totals, landowner names, tax ID #s, etc.). What I ultimately need is a .csv file with all of ...
7
votes
3answers
4k 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 ...
18
votes
1answer
4k views

Calculating Flow Direction and Delineating Basins from Projected vs. Unprojected DEM Data

This is somewhat of a theoretical question stemming from some discussions with colleagues on the topic of implications with delineating basins with projected (e.g., Albers Equal Area) vs. unprojected ...
10
votes
4answers
3k views

Code to calculate elevation profile along line from a DEM

Given a DEM (Digital Elevation Model) say in and a line (x1,y1) --> (x2,y2) (paired coordinates (x,y)), how can one calculate the elevation profile or cross-section projected on that line ? I am ...
14
votes
2answers
5k views

How can I switch baselayers as a user zooms in to the map in OpenLayers

I have a map which overlays Open Street Map data on imagery for Pennsylvania. As a baselayer to the roads (and eventually other layers) I have two baselayers - Blue Marble NG and USGS EROS 1ft ...

15 30 50 per page