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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16 views

3D topographic progress compensation by the least squares method

I'm looking for an explanation of the least squares method used in the case of a correction of 3D point network. We have reference points with known coordinates XYZ. We calculate intermediate points ...
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1answer
32 views

How to combine depth and topography .asc file?

I have a .asc file produced from a hydraulic model. The .asc file contains depth data of flood inundation. I want to superpose the depth asc file with my topography .asc file so I can identify where ...
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46 views

Finding Color Palettes?

Anybody can help me to find the three color palettes of the following map?
3
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1answer
71 views

Correcting for local topography in calculating TRI from DEM in ArcGIS

I'm currently investigating the use of different equipment in calculating TRI from elevation data using ArcGIS. From the methods available ...
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0answers
7 views

Finding ocean topography data for Burma?

I would like to find the ocean topography around Burma. I would like to have a detailed topography at a local scale such as the ocean depth next to Dawei and Thilawa. Where could i find these ...
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1answer
51 views

How to display steep slopes with the use of Contours?

I am using Arc Map 10.1. I have downloaded contour data as a shapefile. Is there any way to use the contours to display steep slopes so 15%-25% or 25% and greater.
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84 views

How can I enhance a topo map I am making as a Christmas gift? [closed]

I am using ArcGIS for Desktop 10.2. I am making a topo map for my girlfriend's brother as a Christmas gift. He is one who will appreciate a good map that was "drawn" in 1958. I know you can ...
5
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0answers
45 views

FLAG - fuzzy landscape analysis in GIS

I am trying to identify wetlands using different topographic indexes, e.g. TWI/CTI. And I would like to try out a method called FLAG (fuzzy landscape analysis in GIS), but I don't really understand ...
2
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1answer
69 views

What is Google's source for topographic data?

I'm looking for as detailed as possible topographic data for a certain area and have found information displayed by Google Maps to be far more detailed than what is provided by 7.5 minute maps (from ...
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1answer
85 views

Learning about bathymetry?

Besides reading about bathymetry, I would like to work on some hands-on training that I can learn about bathymetry. Is there any good bathymetry out there that I can get some training with the ...
5
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2answers
89 views

Software for amateur topographic surveys

I'm interested in doing rough topographic surveys using my tripod-mounted Brunton transit compass for azimuth readings and laser rangefinder (and maybe an optical level), so obviously going to be much ...
2
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1answer
249 views

Detailed topographical map of Istanbul

I need to acquire a very detailed topographic map of Istanbul, Turkey without any markers. Do you know such sources who provides these kind of maps? I tried to Google it, but the results were far ...
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2answers
114 views

Mercator vs. Web Mercator for Large Scale Topographic Maps

I have 8 terabytes of imagery that is in either lon/lat or UTM projection that I will be using for the basis of large scale topographic maps. I have been studying the differences between Mercator and ...
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1answer
40 views

Looking for detailed relief tiles

A few days ago I stumbled over a map which had beautifully rendered, detailed topographic tiles of the whole world. It was similar to google-physical with a strong contrast (shadow/light) and ...
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76 views

Find Average Elevation - ArcGIS Desktop

I am working with 2 shapefiles. One contains the boundaries of a city, the other contains polylines representing the topographic features of the area. Essentially, the polylines make a topographic ...
2
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1answer
767 views

Plotting elevation maps and shaded relief images from latitude, longitude, and elevation pairs

I have a set of latitude, longitude, and elevation pairs (roughly a grid of such values, though it is not uniform), and I'd like to be able to plot an elevation map and perhaps also a shaded relief ...
2
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1answer
39 views

basic understanding of ArcGIS for Flex not clear on the concept

I am a complete newbie to GIS so please excuse the simple question. I am looking for someone to point me in the right direction to get some answers and/or maybe provide links to where I can find some ...
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1answer
60 views

Why do different USGS Topo maps show different elevations for the same control point?

So I have been investigating the area around Jerome and Clarkdale Arizona using different USGS Topographic map sources of the same scale, but different time periods, and find that in some cases, the ...
3
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1answer
235 views

Recommendations for creating contour map from depth points

I am trying to put together a safe routes map for a local lake. I have an old paper map that has a grid of various depths as points. I would like to draw contour lines through these points and create ...
2
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1answer
87 views

How to disassociate roughness from slope

How to measure topographic roughness irrespective of slope in ArcGIS? I have used many methods to generate roughness layers, including TRI, VRM (which is supposed to be less correlated with slope), ...
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0answers
92 views

How to develop an elevation profile tool with high precision? [closed]

Similar to the Google Earth elevation profile tool, also similar to this: http://www.geocontext.org/publ/2010/04/profiler/en/?send_comment=success#comments I want to be able to use my own set of ...
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3answers
74 views

Ontario Topographic and Property Data

Looking for Ontario topographic data and property line data; willing to purchase the latter. Shapefiles or file geodatabase files would be optimal. In terms of topographic data, I am looking for: ...
3
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1answer
112 views

data source for worldwide cross-sections of topographic and bathymetric for woodworking art project?

i am a decent r programmer and statistician, i am able to work with data sets pretty well. i am less familiar with GIS tools, but if given a shapefile i can certainly plot political borders and ...
5
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2answers
232 views

Is there a difference between the Planchon & Darboux and Wang and Liu depression filling algorithms? Other than speed?

Can anyone tell me, based on actual analytical experience, if there is a difference between these two depression filling algorithms, other than the speed at which they process and fill depressions ...
2
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1answer
277 views

Negative Topographic Index Values

I am getting negative topographic index wetness values in SAGA GIS - anyone else every get this? Not all negative values, but the minimum of the TWI range is negative for some steep watersheds we are ...
4
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1answer
252 views

Topographic Index - Why is upslope contributing area divided by downslope contour width and not upslope contour width?

In the Topographic Index calculation, a is the upslope contributing area per unit contour length. Is the "unit contour length" calculated from examining the contour widths of the downslope cells that ...
0
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1answer
68 views

Is there a public CanTopo Web Map Tile Service (WMS / WMTS) available?

Does anyone know of a public CanTopo WMS / WMTS available anywhere? I'm assuming CanTopo is more modern / up-to-date than Toporama? Alternatively, what would be your suggestions for the most pain ...
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2answers
96 views

What USGS maps exist in the 7.5' × 15' metric 1:25,000 series?

While browsing through the library, I discovered that USGS has, in fact, produced some metric maps at 1:25,000. One example is Thendara (NY), 43075-F1-TM-025. As far as I can tell, those maps are ...
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0answers
11 views

Are there any NTS index maps showing the most recent update?

For the Canadian National Topographic System, are there any index maps available that do not only show map numbers throughout the country, but also the most recently available update for each map? As ...
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0answers
157 views

What steps does SAGA GIS take when calculating Topographic Wetness, specifically when handling depression filled (by ArcMap) DEM

I am a grad student involved with hydrological modeling. In the model I work on, we are calculating the Topographic Index (TI; without transmissivity - or set to 1) using Quinn's MFD algorithm. We do ...
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3answers
671 views

Topography: How to get the x,y,z coordinates of highest or lowest point/pixel of a raster GIS?

Given a .tiff topographic raster image with mountains and deep sea, I am looking for the x,y,z specifics of the highest or lowest point. The x,y,z values being: altitude (z-coordinate) latitude ...
2
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2answers
155 views

Gdal: highest and lowest point/pixel, how to get their altitudes?

Given a .tiff topographic raster image. How to get the altitudes of the highest and lowest point/pixel ?
4
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2answers
151 views

Why are poles missing from GIS topographic data?

Why are poles data missing from most topographic resources ? Data from 60⁰ to 90⁰ lat frequently missing from topographic GIS data. Example with SRTM4.1: Common sense or deduction lead me to think ...
3
votes
1answer
278 views

How to create a buffer on a linestring with varying or increasing/decreasing width

I want to buffer rivers/streams for a topographic map. I'm using a PostgreSQL/PostGIS database. Usually, I create buffer with ST_Buffer with a constant width. For example, the width of a river buffer ...
5
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1answer
363 views

Calculating Topographic Exposure with Raster Calculator

I need you help trying to calculate Topographic Exposure (TOPEX) on a DEM in ArcGIS. I am trying to figure out wind exposure on a DEM with 25m cells. There is a great blog post where someone explains ...
3
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0answers
132 views

How to compute surface of raster or any point using ARCGIS?

I have a raster image whose values are a digital elevation model of terrain. I need to know the surface type (topographic characterization) of particular points along transects of this DEM. How to ...
4
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2answers
1k views

how do you identify ridges on an elevation raster?

I was wondering whether anyone might be able to tell me in layman's terms how to extract or differentiate between ridges and hilltops from 10m elevation data using ArcGIS 10.1? Any advice would be ...
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1answer
42 views

Rough edges on tiles in QGIS

I'm loading four .ASC files into QGIS, each containing topographical data about a tile of 10 x 10 km. On the map, this data is displayed as black/white and different shades of gray. My problem is that ...
5
votes
2answers
974 views

What's the difference between hypsography and topography?

I've recently come across some data that has been labeled "hypsography". I looked it up and it sounds like topography. But this data source has data labeled "topography" separate from its ...
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2answers
295 views

Where can I programmatically download SRTM_V4.1 data?

SRTM v4 is an effort by the folks at CIAT-CSI to scrub, polish, and remove gaps in the raw SRTM data released by NASA (SRTM 3). One userfriendly interface : http://dwtkns.com/srtm/ provides ...
2
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1answer
1k views

Polygonize.py outputs into a single file or simple merge?

Given an unique raster topographic file at start, I want to get vector polygons for elevations thresholds 1m, 200m, 500m, 1000m, 2000m into a single shp file. I first slice my raster into 5 (or more) ...
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1answer
424 views

How to conditionnally assign a new value to pixels of a raster image?

Given a topographic GIS raster of one country crop.tif: Given a know pixel value such as elevation (z) is +73 : $ gdallocationinfo crop.tif 1 1 -valonly > 73 Given an elevation threshold n = 50 ...
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2answers
383 views

Gdal: How iterate through all pixels of a raster image?

Given a topographic raster image. How to iterate through all pixels of this raster image ? Solution preferably with gdal, in console. Some other libraries/script could be installed. Related: ...
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1answer
425 views

Gdal: How to get a pixel's value from raster image?

Given a topographic raster image. Given a pixel's coordinate in pixel/lines or geocoordinate. How to get it's pixel value ?
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1answer
211 views

Gdal_polygonize: How to filter pixels above a given value (elevation)?

Given a topographic GIS raster of one country: Given an elevation threshold n = 50 (meters) How to polygonize pixels when z >= n ? gdal_polygonize.py is not clear on this point. It states This ...
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0answers
453 views

Topography: How to convert raster into vector layers?

(nb:This project is part of the #Wikipedia #wikimaps project) 1. Question: How to create vector topographic maps from raster image ? How to convert raster topographic image into closed vector ...
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0answers
485 views

How to limit a specific area in order to have a topographic 3D map using MatLab?

I am using MatLab, I want to build a topographic 3D map, I am following this guide, I have been doing the steps listed on the section Draping Geoid Heights over Topography, and I do not have any ...
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163 views

cut/fill calculation tool to investigate if there is enough material to achieve a 30 degree slope

This is a cut/fill problem. We have pits that have been dug in the ground, usually rectangular. They have a bund wall around them. They are being rehabilitated by pushing the bund back into the pit. ...
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187 views

How to calculate Gradient from DEM?

I have a digital elevation model for a catchment area and I would like to calculate the gradient by cells. Is that possible and does anybody know the steps?
2
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1answer
614 views

European Mountains Shapefile Data Sources

I am trying to locate a GIS freely downloadable shapefile (preferably polygon) of European main mountain chains (not an elevation data), eg Alps, Carpathian Mountains. I tried variuos sources , ...