22
votes
3answers
5k 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
39k 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
5answers
5k 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 ...
18
votes
1answer
3k 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 ...
14
votes
5answers
10k 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 ...
26
votes
4answers
5k 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) ...
18
votes
2answers
7k views

How to convert an .mxd file to a .qgs file?

I recently tried to use QuantumGIS and I wondered if you can turn in a draft format ESRI mxd loadable qgs. This would avoid thematize the entire project. Thanks for your help.
16
votes
3answers
3k 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 ...
29
votes
4answers
4k 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 ...
20
votes
5answers
9k 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 ...
15
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
3k 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 ...
15
votes
10answers
6k 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?
14
votes
7answers
5k views

Nearest neighbor between a point layer and a line layer

I've asked this question several times on stackoverflow and irc between #qgis and #postgis and I also tried to code it or implement it my self in postgis with no real answer. Using programming (most ...
22
votes
6answers
860 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
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 ...
12
votes
6answers
3k views

ArcObjects Resources

What are the best books/web sites for C# development with ArcObjects? The ArcGIS Resource Center is very helpful, but I am trying to find sources with more examples. Thanks
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 ...
18
votes
4answers
5k 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 ...
13
votes
5answers
1k 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 ...
13
votes
4answers
640 views

Migrating to Linux from Windows

I am looking at switching over a computer from Windows to Ubuntu. I have been a Windows user all my life and been using GIS for over a decade. I am curious about the migration to Ubuntu. Mostly, ...
13
votes
2answers
4k 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 ...
12
votes
2answers
5k views

Specifications for GIS desktop hardware

I'm in the market for a new pc/laptop. Judging from what I've seen around here, a lot of people are discussing having a laptop for their personal GIS use. Portability is not an issue for me, so I'm ...
12
votes
4answers
1k views

comparing two DEMs

i have two Lidar las files, one is original let's say with X points. And the other is copy of the first las file but with Y points, where Y is less than X. Now, i wanted to compare how the Digital ...
22
votes
4answers
10k 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' - ...
14
votes
4answers
6k views

Join non-spatial CSV to spatial data in QGIS

I have a csv which has postcode data in a field, but it is non-spatial e.g. no Easting and Northing. I have a shapefile with postcode in a field and some additional data. I want to join the csv with ...
8
votes
2answers
1k views

How to count and rasterize polygon overlaps in ArcGIS?

How do you take a vector layer with overlapping polygons and turn it into a raster where each cell counts the number of polygons containing that cell? We are looking at polygons of fire burn areas ...
8
votes
1answer
1k views

How to reproject a raster file in QGIS with datum transformation?

I want to reproject a tiff raster file from projection A (ETRS89/UTM Zone 32) to projection B (DHDN/Gauss-Kruger zone 2). The two projections have a different datum so I have to use a datum ...
8
votes
2answers
3k views

How to check Topology in QGIS?

I have two Shapefiles with Polygons ( City and Forerst) Is there a Plugin who is able check the topology (QGIS)? Like "Knots do not overlap" or something like that? I dont want that they overlap. ...
6
votes
3answers
7k 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
6
votes
2answers
4k 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
5k 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 ...
10
votes
2answers
2k views

Is it possible to export GeoPDF from QGIS?

Is their any plugin for QGIS which would help me in exporting the map document as a GeoPDF ?
7
votes
1answer
1k views

Postgresql for Qgis and Arcgis - What to do/What not to do

Is it possible to use postgresql with QGIS and ArcGIS? One database for different clients. Is it anything that I have worry or any problems to use the DBMS from two different software? I know that I ...
7
votes
4answers
3k views

Site to download al USGS Topo Maps in bulk

I am trying to create seamless topomap WMS or TMS layer that covers the entire US (not interested in geo-pdfs). To do that, I need either the rasters (geo-tiffs, etc) or preferably vectors (whatever ...
6
votes
1answer
958 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? ...
17
votes
3answers
531 views

How much Water on Earth(USGS) : A Wrong Map representation?

I happened to read a USGS article, How much water is there on, in, and above the Earth? showing a representation of all the water(which includes water from Oceans, Seas,Bays,Ice caps, Glaciers, ...
13
votes
1answer
1k views

Voronoi polygons that run out to infinity

I have been working on implementing the voronoi.py script (Bill Simon's translation of Steve Fortune's code). According to the QGIS link it is basically the same code that I am working with, but the ...
11
votes
6answers
882 views

How to implement value-by-alpha map in GIS?

I've been doing some background reading about cartograms recently and stumbled upon interesting alternative - value-by-alpha maps. Concept is described in more details here and full paper is ...
8
votes
1answer
1k views

How to compute the bounding box of multiple layers in lat/long?

I am writing an application to performance test all kinds of map services, primarily AGS 9.x, AGS 10, and WMS 1.x. Part of the application involves generating random bounding boxes for individual ...
7
votes
3answers
4k 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
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
3answers
3k views

Why don't my Shapefiles and OSM data overlap in Quantum GIS?

So I'm pretty new to GIS, and I'm working on a mapping project using data for Vancouver, Canada. I want to combine Open Street Map data along with data provided by the City of Vancouver. But the City ...
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
5k 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
3k views

Interpretation of ArcGIS Kernel Density legend parameters

In ArcMap 9.3 I've used Kernel Density to map various incidents, but the resulting shapefile doesn't display any units of measurement. Is there a good, not-to-technical source that would explain in ...
3
votes
1answer
2k views

Elseif Conditional Statement in QGIS Field Calculator

I am trying to write an ELSEIF conditional statement in QGIS Field Calculator (version 1.8.0). I have used an example I found online: CASE WHEN val < 0 THEN 'negative' WHEN val = 0 THEN ...
2
votes
1answer
429 views

Help with Python script for exporting mxds into pdfs!

I have written a python script to export my mxd into a pdf (not using data driven pages). I am getting the error that my mxd path is incorrect! I have included my script below. Any help would be ...
10
votes
4answers
806 views

How to calculate the visible sky percentage

Hi I am writing a project and I am stuck: can anyone explain as simply as possible how to calculate the visible sky percentage? I have done a satellite survey and have worked out the height of ...

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