194
votes
5answers
154k views

How to measure the accuracy of latitude and longitude?

I am very new to GPS stuff. Suppose I have latitude and longitude as 19.0649070739746 and 73.1308670043945 respectively. In this case both coordinates are 13 decimal places long, but sometimes I also ...
184
votes
50answers
66k views

What Makes a Map Beautiful? [closed]

Oftentimes when we make maps it is based on our subjective interpretation of what is aesthetically pleasing. I would like it if people posted examples of beautiful maps, displaying any phenomena in ...
173
votes
11answers
62k views
142
votes
42answers
15k views

What free programs should every GIS user have installed?

Note: This question is specifically about installed, desktop software. There is another question specifically about free cloud-based software and services. What free programs should every GIS user ...
138
votes
18answers
60k views

How do various JavaScript mapping libraries compare?

I am working on a web-based mapping system and I'm trying to figure out the best/most appropriate library to use. There are a few of them about and they each have pros and cons. Even after trying a ...
101
votes
5answers
17k views

How do I access ArcObjects from Python?

I would like to be able to script some things that are not exposed via arcgisscripting or ArcPy. How do I access ArcObjects from Python?
94
votes
13answers
5k views

How to account for Colour Blindness when designing maps?

Depending on what you read, 7 to 15% of the general population has some form of colour blindness. That's a significant amount of people. Do you try to account for this in your map designs? If so, how? ...
92
votes
4answers
67k views

File Geodatabase (*.gdb) support in QGIS?

Following questions: Open Source Tool capable of reading Esri File Geodatabase (.gdb)? How to access file geodatabase in Qgis? How to get FGDB support in GDAL 1.9 without compiling? I have spent ...
89
votes
13answers
29k views

What are Definition, Algorithms and Practical Solutions for Concave Hull?

Convex Hull A convex hull of a shape is defined as: In mathematics, the convex hull or convex envelope for a set of points X in a real vector space V is the minimal convex set containing X (...
83
votes
30answers
35k views

How to Start Web Mapping?

I want to start working on a web map at work to map some of our statistics by city. I have an idea, but I'm not exactly sure where to start. Are there any definitive resources that provide step ...
80
votes
3answers
64k views

EPSG 3857 or 4326 for GoogleMaps, OpenStreetMap and Leaflet

The discussion at What is the difference between WGS84 and EPSG4326? shows that 4326 is just the EPSG identifier of WGS84.. Wikipedia entries for Google Maps and OpenStreetMap shows that they both ...
78
votes
20answers
75k views

How to convert between KML and Esri's shapefile (SHP) format?

My users are sending me point data that were digitized using GoogleEarth. How can I convert their KML to a shapefile?
76
votes
25answers
6k views

What books, journals, and electronic resources are most valuable for expanding knowledge of GIS? [closed]

What books, journals, and/or electronic resources have you found most valuable for expanding your knowledge in the GI field? To which of them you come back most often? One item per post please, and ...
76
votes
14answers
12k views

How much math does a GIS Analyst need to know?

For someone studying to pursue a career as a GIS Analyst, what math courses should he/she take? Update Here's a long list of free Math courses from MIT to serve as a frame of reference. Which are ...
75
votes
9answers
10k views

Getting started with PostGIS?

I have been reading a lot about PostGIS, but I am struggling to find a good beginner's guide. Which tutorials/books do you recommend?
72
votes
19answers
6k views

How do I explain what GIS is for the 11 year old kid?

Well, since it was one of the highest rated proposed questions, hasn't been asked yet, and I would love to know the answer, I thought I'd ask it. How do I explain what GIS is for the 11 year old kid?
72
votes
11answers
23k views

What Makes a Map be classed as Badly Designed?

A poorly designed map can not only look visually unappealing, but can convey the wrong message, which could lead to bad decisions being made. I would like to ask people to post examples (that are in ...
70
votes
7answers
8k views

Managing large amounts of geospatial data?

How do you manage your geospatial data? I have terabytes of data spread out over hundreds of datasets, and have an ad-hoc solution using symbolic links within projects which link back to an domain-...
66
votes
5answers
23k views

Spatial clustering with PostGIS

I'm looking for spatial clustering algorithm for using it within PostGIS-enabled database for point features. I'm going to write plpgsql function that takes distance between points within the same ...
65
votes
5answers
34k views

How to build effective heat-maps?

Using ArcGIS, QuantumGIS, Grass, and/or GVSIG What are some of the tools and processes involved in building effective heat maps? What are the plugins involved? What are the major data requirements? ...
64
votes
18answers
81k views

List of GIS applications for Android Tablets

I know that ArcGIS will someday be available for Android, but does anyone know of any other GIS apps that are available for Android tablets?
63
votes
13answers
52k views

Installing GDAL with Python on windows?

Can anyone explain how to install GDAL/OGR with Python on Windows? I have Windows Vista and I have tried following the information on the website and it does not seem to bind the exe files for me. ...
60
votes
7answers
85k 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: DEM: Digital Elevation Model DSM: Digital Surface Model DTM: Digital ...
58
votes
6answers
8k views

When to use ModelBuilder over Python scripting and vice versa?

I am new to Python scripting in ArcGIS but not new to ModelBuilder. I would like to know the benefits of Python vs ModelBuilder. When should we write Python script for GIS automation rather than ...
58
votes
6answers
33k views

Should I use OpenLayers or Leaflet?

I was debating with one of my collegues on OpenLayers v/s Leaflet. I made a point that OpenLayers is much better API if we wish to build a project, where you need direct connectivity to the Geoserver ...
58
votes
7answers
2k views

Are there any attempts to replace the shapefile?

Recently I've been spending a lot of time converting perfectly good field names like "Percent of citizens age 25 and over with a bachelor's degree or higher" into things like "edbchogtr" to meet the ...
57
votes
3answers
78k views

Algorithm for offsetting a latitude/longitude by some amount of meters

I'm looking for an algorithm which when given a latitude and longitude pair and a vector translation in meters in Cartesian coordinates (x,y) would give me a new coordinate. Sort of like a reverse ...
57
votes
3answers
51k 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.
56
votes
12answers
5k views

Visualizing speed of movement on static (= printable) map?

Imagine you're tracking, for example, vehicle or animal movement and receive regular GPS position updates. How would you visualize speed of movement on a static (= printable) map? I've been coloring ...
55
votes
14answers
5k views

The GIS of War - Tracking Conflicts and Their Effects

I was idly speculating on the many sorts of things people are keeping track of these days with GIS - natural/human catastrophes, demographic and economic patterns, climate change, etc. In that vein, I ...
55
votes
11answers
23k 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 ...
54
votes
19answers
40k 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?
54
votes
10answers
5k views

Alternatives to using Arcpy

I seem to use ESRI's Arcpy site package for virtually all of my python geoprocessing. To ESRI's credit, these are an incredible suite of tools that can help accomplish a great deal. However, I would ...
54
votes
19answers
13k views

Where to find QGIS tutorials and web resources?

I wish to familiarize myself with the capabilities of QGIS. I have downloaded the program, but apart from basic loading of data, I am lost (even after reading the help file). Can you recommend me ...
53
votes
8answers
2k views

One dimensional map of the world?

Bit of a strange question but hope this is OK to ask here. Has anyone heard of a '1-dimensional' projection of the world map - that is mapping all the points on the globe to a single line? I was ...
53
votes
5answers
83k views

How to add Basemaps from Google or Bing in QGIS?

Like ArcGIS Desktop has the option of using basemaps from ArcGIS online, does QGIS have any such options?
52
votes
38answers
6k views

What is the most annoying fact about the GIS market/industry? [closed]

What are the most annoying facts about our industry/market? What makes you angry? Is there anything that you can't stand it?
52
votes
18answers
69k views

Free administrative boundaries available as shapefiles for United Kingdom, New Zealand, Canada and Italy?

After learning about the US Census's TIGERLines datasets I've working with the following layers, from the USA data Country boundaries State boundaries County boundaries City boundaries ZipCode ...
52
votes
5answers
3k views

How to calculate most efficient route passing through all the houses in the world?

I'm new to GIS. I need some help in determining the best or most efficient route, using a flying sleigh, through all the houses in the world. One of my coworkers told me that this site would be the ...
52
votes
3answers
18k views

Openlayers Animation Examples and Algorithms

i wonder for a long time if people in this community uses openlayers for animation needs. we have know this that animating on browser is a little bit exhausting for it but when a map meets with ...
51
votes
12answers
102k views

What ratio scales do Google Maps zoom levels correspond to?

Can anyone provide me with a link (or some details) on the actual ratio to "zoom level" figures for Google Maps? e.g. Google Maps Level 13 = 1:20000
51
votes
7answers
5k views

What strategies, criteria, or rules to use for selecting coordinate systems?

What strategies, criteria, or rules do you use for selecting coordinate systems for (a) storing, (b) analyzing, and (c) displaying GIS data? (I humbly offer my reply to a related question ...
50
votes
8answers
10k views

How to create Vector Polygons at the same amazing speeds GISCloud is able to render them?

EDIT (outlining new bounty added): I have added the largest bounty possible to this question in hope of getting a very detailed answer. Your solution should outline a step-by-step guide utilizing open ...
50
votes
6answers
20k views

What are Esri's new “ArcGIS for Professionals” and “ArcGIS Pro”?

After looking through all the stuff that was released or talked about at the Esri UC 2013 I am still genuinely confused by what ArcGIS for Professionals is. I will admit that it looks pretty cool, ...
49
votes
15answers
24k views

Resources for learning Python programming with generic GIS goals in mind?

In your opinion, what is the best book/site to learn Python with GIS goals in mind? By "best", I mean: not very long (book) easy to understand (book/site) good practical examples (book/site) For ...
49
votes
4answers
13k 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 ...
49
votes
4answers
18k views

LatLon or LonLat, what's the “right” way to display coordinates and inputs?

I'm trying to get a sense if this is an issue for others or every input/output should be labeled so user is not confused and just go with it? I think almost everyone pronounces it as "LatLon". Who ...
48
votes
11answers
22k views

Identifying Coordinate System of Shapefile when Unknown?

I have a Shapefile but its coordinate system is Unknown, and there is no *.prj file. How I can identify it now? Are there any tools that could help?
48
votes
2answers
7k views

Acquiring ArcGIS-like speed in Postgis

I have been using Postgis 2.0 for 3/4 of a year now and while I really enjoy using it, excessive query processing time has rendered it basically unusable for my use case. I tend to do heavy ...
48
votes
4answers
8k views

Why has Web Mercator (auxiliary sphere) become the web map standard?

I understand what the difference is between the Web Mercator projection and Web Mercator Auxiliary Sphere (WMAS). I also understand that both Google and Esri have adopted this projection as their ...

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