Monthly Archives: May 2014
New Desktop or Laptop computers usually come with two internet adapters, Ethernet and wireless. If you only use the Ethernet port for your computer, then you can share you PC’s internet as a WIFI hotspot via the wireless adapter. The easiest way to use Virtual Router Plus. You can download it from the link below. Just unzip the downloaded zip file, and double click the VirtualRouterPlus.exe to run. Click “Start Virtual Router Plus”, then you are good to go.
If Virtual Router Plus does not work, you can try mHotspot.
Two new GIS online courses available on Lynda.com. Good resource for GIS beginners.
- Up and Running with ArcGIS
- Real-World GIS
TRAINING STUDENTS TO EXTRACT VALUE FROM BIG DATA
Keck Center of the National Academies
500 5th St NW, Washington, DC 20001
A Workshop of the Committee on Applied and Theoretical Statistics
Sponsored by the National Science Foundation
John Lafferty, University of Chicago (co-chair)
Raghu Ramakrishnan, Microsoft Corporation (co-chair)
Deepak Agarwal, LinkedIn
Corinna Cortes, Google
Jeff Dozier, University of California, Santa Barbara
Robert Kass, Carnegie Mellon University
Anna Gilbert, University of Michigan
Rafael Irizarri, Harvard University
Patrick Hanrahan, Stanford University
Prabhakar Raghavan, Google
Nathaniel Schenker, Centers for Disease Control and Prevention
Ion Stoica, University of California, Berkeley
Friday, April 11th
Breakfast available in the meeting room beginning at 8:00 AM
8:30-8:40 Opening Remarks
Deputy Assistant Director
Directorate for Computer and Information Science and Engineering
National Science Foundation
8:40-10:00 The Need for Training: Experiences and Case Studies
Raghu Ramakrishnan, Microsoft Corporation
John Lafferty, University of Chicago
Rayid Ghani, University of Chicago
Guy Lebanon, Amazon Corporation
10:15-12:45 Principles for Working with Big Data
Chair: Brian Caffo, Johns Hopkins University
Jeffery Ullman, Stanford University
Alexander Gray, Skytree Corporation
Duncan Temple Lang, University of California, Davis
Juliana Freire, New York University
1:45-4:15 Courses, Curricula, and Interdisciplinary Programs
Chair: Jim Frew, University of California, Santa Barbara
Bill Howe, University of Washington
Peter Fox, Rensselear Polytechnic Institution
Joshua Bloom, University of California, Berkeley
Saturday, April 12th
Breakfast available in the meeting room beginning at 8:00 AM
8:30-11:00 Shared Resources
Chair: Deepak Agarwal, LinkedIn
Christopher Re, Stanford University
Bill Cleveland, Purdue University
Roger Barga, Microsoft Corporation
Ron Brachman, Yahoo
Mark Ryland, Amazon
11:15-1:00 Panel Discussion: Workshop Lessons
Chair: Rob Kass, Carnegie Mellon University
Interesting to see the “energy” concept, which seems similar to the least-cost algorithm. Will check it out. Thank you!
In my last posts I wrote about carving and filling. As noted, both algorithms are implemented in the constructor function FLOWobj and thus are primarily used to derive flow directions through topographic depressions. These options, thus, don’t change the DEM itself. In this post, I will show how you will carve and fill the DEM.
Filling is easy and implemented in most terrain analysis software. A number of different algorithms exist that perform flood-fill operations; in our paper, Dirk and I compared processing speeds to fill an image. We found that the speed at which one and the same DEM is filled varies widely between different software. The Matlab’s image processing toolbox’s function imfill (the function that is called by TopoToolbox function fillsinks) outperforms other software by 8-10 times faster processing speed. However, I like to stress that speed is not the only indicator of performance and that other…
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- Download and install Eclipse
- Download Eclipse standard version: http://www.eclipse.org/downloads/packages/eclipse-standard-432/keplersr2
- Extract the downloaded zip file, copy the unzip “eclipse” folder to C:\Program Files\.
- Install PyDev for Eclipse
- Go to Eclipse –> Help –> Install New Software
- Enter http://pydev.org/updates in the Work with: field.
- After several seconds, two options should appear. Select the PyDev for Eclipse option. Do not select the “PyDev Mylyn Integration” flag.
- Click “Next” and “OK” to continue installing PyDev
- Configure PyDev
- Go to Window → Preferences. In the Preferences window, expand PyDev and select Interpreter-Python.
- Click “New…” and type Python27 for the Interpreter name. For the Interpreter executable, browse to your copy of Python C:\Python27\ArcGIS10.2\python.exe), and press Open.
- Click “OK” and the Selection Needed Window will appear.
- Click “Select All” and “OK”.
- The Interpreter is now set up so that the code you write can be interpreted for the computer to run. You are now ready to start running code.
- Open Perspective as PyDev
ArcGIS Online is a powerful platform for analyzing data. New spatial analysis tools are being continually added to help you solve common spatial problems. If you would like to learn more about online analysis, tune into the live training seminar Spatial Analysis with ArcGIS Online on May 15, 2014.
People using TopoToolbox asked me quite frequently about the difference between the two preprocessing options when calculating a flow direction object (FLOWobj): ‘carve’ and ‘fill’.
First and most important: These options do not alter the DEM, they only control how FLOWobj internally preprocesses the DEM to optimize how flow is routed through topographic depressions.
In this first post I’ll describe how the option ‘fill’ works.
Option ‘fill’: The constructor function FLOWobj fills all topographic depressions (function fillsinks). It then identifies all flat sections (function identifyflats) and calculates an euclidean distance transform (function bwdist) within each flat section seeded at their outer rim. Subsequently, the complement of the distance transform is calculated in each flat area. The complement grid is subsequently used as weights in a gray-weighted distance transform (function graydist). This generates an auxiliary surface in each flat area. The surface has the nice property that flow will run through…
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A new great tool in Whitebox GAT
I just finished developing a tool for Whitebox GAT that will automatically download Shuttle Radar Topography Mission (SRTM) digital elevation models (DEMs) from the USGS SRTM FTP site. SRTM-3 data are among the best global elevation data, with a grid resolution of approximately 90 m. In many areas SRTM data provide the only topographic data set available. Within the United States, the SRTM-1 dataset provides an improved 30 m resolution. Not only does this Whitebox tool retrieve the SRTM tiles contained within the bounding box of a specified area of interest, but it will also import the tiles to Whitebox GAT, fill missing data holes (which are common with SRTM data in rugged terrain) and mosaic the tiles.
There have been many times in the past when I have needed to download numerous SRTM files, import the files, fill the missing data holes, and finally mosaic the…
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