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Posts Tagged ‘DEM’

Download Arctic area digital elevation data from ArcticDEM

December 22, 2019 Leave a comment

Here we are at the winter solstice in the Northern Hemisphere and it seems appropriate to discuss polar data.  ArcticDEM is an NGA (National Geospatial Intelligence Agency) – NSF (National Science Foundation) public-private initiative to produce a high-resolution (2 meter), high quality, digital surface model (DSM) of the Arctic using optical stereo imagery, high-performance computing, and open source photogrammetry software.  The majority of ArcticDEM data was generated from the panchromatic bands of the WorldView-1, WorldView-2, and WorldView-3 satellites. A small percentage of data was also generated from the GeoEye-1 satellite sensor.  The resource covers all land north of 60 degrees north latitude.  Yes!  Not only Alaska, but Scandinavia, Russia, Canada and Iceland.  For more information, see this page.  For a web mapping application the Arctic DEM Explorer from Esri, see this page, and for the bare-bones but useful file index for fast downloading, see this page.

In my opinion, the most useful site about Arctic DEM for downloading the data is this web mapping application, the ArcticDEM index and data download.  This application allows a user to select specific index tiles of digital elevation model data.  The tiles reveal information about the DEM tile and a download web URL.  Each cell is about 2GB, with over 18 TB on the entire site.  Truly a treasure trove of data!  For selecting multiple indices, use the ‘Query’ tool to draw an area and return information on intersecting DEM tile indices. You can export these results for your reference which also include the download web URLs.

Click on any location for attribute information.  Find the “fileurl” attribute, click on More info, and then you will be able to download the 2 meter elevation data for that location.  The query widget allows for the retrieval of information from source data by executing an intersect query either against 2m DEM strips or 2M DEM mosaics.   The resource also includes a swipe tool where you can compare the content of two different layers on the map, such as the index layer and the hillshade.

The best news about this resource, and consistent with our continued mantra about GIS as a SaaS, may be that the site allows for the data to be examined as an ArcGIS Online item and also as an image service via a URL.

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Interface of the Arctic DEM Index and Data Download resource. 

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The Arctic DEM data streamed and viewed in ArcGIS Online. 

I look forward to hearing your reactions to this resource.

–Joseph Kerski

Spatial Analyst videos describe decision making with GIS

I have created a series of 22 new videos describe decision making with GIS, using public domain data.  The videos, which use the ArcGIS Spatial Analyst extension, are listed and accessible in this YouTube playlist.  Over 108 minutes of content is included, but in easy-to-understand short segments that are almost entirely comprised of demonstrations of the tools in real-world contexts.  They make use of public domain data such as land cover, hydrography, roads, and a Digital Elevation Model.

The videos include the topics listed below.  Videos 10 through 20 include a real-world scenario of selecting optimal sites for fire towers in the Loess Hills of eastern Nebraska, an exercise that Jill Clark and I included in the Esri Press book The GIS Guide to Public Domain Data and available online.

New Spatial Analyst videos explain how to make decisions with GIS.

New Spatial Analyst videos explain how to make decisions with GIS.

1)  Using the transparency and swipe tools with raster data.
2)  Comparing and using topographic maps and satellite and aerial imagery stored locally to the same type of data in the ArcGIS Online cloud.
3)  Analyzing land cover change with topographic maps and satellite imagery on your local computer and with ArcGIS Online.
4)  Creating a shaded relief map using hillshade from a Digital Elevation Model (DEM).
5)  Analyzing a Digital Elevation Model and a shaded relief map.

6)  Creating contour lines from elevation data.
7)  Creating a slope map from elevation data.
8)  Creating an aspect (direction of slope) map from elevation data.
9)  Creating symbolized contour lines using the Contour with Barriers tool.
10)  Decision making using GIS:  Introduction to the problem, and selecting hydrography features.

11) Decision making using GIS:  Buffering hydrography features.
12)  Decision making using GIS:   Selecting and buffering road features.
13)  Decision making using GIS:  Selecting suitable slopes and elevations.
14)  Decision making using GIS:  Comparing Boolean And, Or, and Xor Operations.
15)  Decision making using GIS:   Selecting suitable land use.

16)  Decision making using GIS:  Selecting suitable land use, slope, and elevation.
17)  Decision making using GIS:   Intersecting vector layers of areas near hydrography and near roads.
18)  Decision making using GIS:  Converting raster to vector data.
19)  Decision making using GIS:  Final determination of optimal sites.
20)  Creating layouts.

21)  Additional considerations and tools in creating layouts.
22)  Checking Extensions when using Spatial Analyst tools.

How might you be able to make use of these videos and the processes described in them in your instruction?

Exploring the US Interagency Elevation Inventory

December 22, 2013 1 comment

The US Interagency Elevation Inventory offers the ability to display and download topographic and bathymetric data for the USA.  A collaborative effort from NOAA, USGS, and FEMA, the resource contains DEM, Lidar, IFSAR, hydrographic surveys, and multibeam and Lidar bathymetric data.

The site hosts have done a decent job populating the metadata, including vertical accuracy, point spacing, and data collection, and the inventory contains a good variety of data types and formats.  To get started, visit the link above and then “Launch the Viewer.”

In my case illustrated below, I was searching for Lidar data for the area around Meteor Crater, Arizona.  After finding it, I was then placed on Open Topography’s site at SDSC for the whole country, requiring me to select my desired area in Arizona again on this new map.  Oddities like this are common to federal data portals, as we document in our book.  Despite this, the US Interagency Elevation Inventory is a useful resource for elevation data.  

Downloading elevation data from Elevation Inventory.

Downloading elevation data from Elevation Inventory.

How might you be able to use this resource?  We look forward to hearing your reflections.