The study and mapping of land surfaces, including relief (relative positions and elevations) and the position of natural and constructed features.

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486 views

What are Bands, Dimensions, and Histograms in QGIS?

First; I can see a band as synonymous with a channel in an image editing program like GIMP, is this correct? If so then bands play the role of color mixing and masking. Are there any other ...
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0answers
32 views

Library for parsing scientific PDS files?

Does a library exist for parsing the PDS files that scientific planetary data gets shipped as? For example, here's a link to to the lunar topographic data from the Lunar Reconnaisance spacecraft ...
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1answer
165 views

I want to create my own topographic map

I need to create topographic maps for scales between 1:100,000 and 1:500,000. This is due to the fact that the official topographic maps in my country are offered in 5k, 10k, 25k, 50k, 100k and 500k. ...
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1answer
3k views

Can Compound Topographic Index (CTI) / Topographic Wetness Index (TWI) produce negative values?

I am calculating Topographic Wetness Index for a study area using SRTM DEM (90 and 30m). I've seen several versions of TWI (CTI). I have been using: TWI = ln(As +1 / tanB) where As = ...
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3k views

Calculate Topographic wetness index in SAGA

i am currently working on a project which involves the quantification of the wetness in certain areas. However it produces quite different results from what i expected. I'll describe the steps i have ...
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418 views

ArcGIS Online Topo Maps

ArcView 10.1 does not have this kind of topo map to "Add Data". Where do I find this type of topo map, preferably free. ArcGIS online does not seem to offer this type of topo, unless I am not seeing ...
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902 views

What are common methods for converting raster digital elevation data to vector contours?

In researching this I have found many references to the opposite, creating elevation data from contours, but nothing regarding contour creation. Preferably, I am looking for open source solutions like ...
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654 views

USGS Topographic Map Online API

I am creating a website for a non-profit organization and would like to plot points on a map similar to this: http://www.arcgis.com/home/item.html?id=931d892ac7a843d7ba29d085e0433465 I am currently ...
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4answers
3k views

Add UTM labels to grid in qgis

I try to use qgis to create a custom topographic map for outdoor use: UTM, 1:50000. What these maps usually have is a 1km x 1km grid, which at the bottom is labeled with a shorthand for the ...
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1answer
853 views

Terraserver replacment - source for US Topo maps?

Now that Terraserver has been shut down (or at least that's how it appears), is there an alternative WMS server for US topo maps? Probably too much to hope to find one that provides vector layers ...
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249 views

Plotting Smith and Sandwell global seafloor topography grids

Does anybody have any experience with plotting Smith & Sandwell 2-minute Mercator-projected grids in ArcGIS? I've downloaded one in two formats: ers and img. I've found tools for processing .img ...
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391 views

How to restrict or block certain paths in NetworkX graphs?

I am trying to calculate shortest path between 2 points using Dijkstra and A Star algorithms (in a directed NetworkX graph). At the moment it works fine and I can see the calculated path but I would ...
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1k views

Map Grid Index / Reference for Canadian Topo Map

Does anyone know where I can find some kml at different resolutions to show the grid reference for the Canadian topographic maps (CanTopo and toporama). Much like is displayed on the map here: ...
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4answers
2k views

How to aquire a topographical map of Britain?

First of all, let me say that I know next to nothing about GISs. I'm trying to find / make / aquire a topographical map of britain. I want to use it as a height map in Dwarf Fortress so it needs to ...
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3answers
713 views

Australian Topo Map GeoTIFFs

Does anyone know if Australian topo map GeoTIFFs are made available anywhere (preferably for free)? LINZ makes them available in New Zealand - http://www.linz.govt.nz/topography/topo-maps/index.aspx ...