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12 Aug 2016

The Great American Eclipse of August 21, 2017

Posted by Tony Soeller. No Comments

Start your travel plans to be in place for The Great American Total Solar Eclipse of August 21, 2017.  This magnificent eclipse will cross twelve States and it surely will be the eclipse of a lifetime!  It would be a HUGE disappointment if you are not standing at the centerline of the eclipse on August 21, 2017.

Here are some relevant links.  Use this first one to zoom in and click on a spot to determine how long the eclipse will last at any one location.


To determine local time subtract local daylight savings time differential from Universal Time (UT).  For instance, in central Oregon (Pacific Daylight Time) subtract 7 hours from UT for the eclipse.  So, there, mid-eclipse will be 17:17 – 7 or 10:17 a.m.

Here’s NASA’s detailed information on this specific eclipse with additional links to other future eclipses around the world:

This following link shows a cool map (click to zoom in) across the U.S. with local details of eclipse information:

Plan your eclipse trip so that you will be right in the center of this map somewhere in the U.S., such as Hopkinsville, Kentucky, right near the point of greatest eclipse.

Here’s a link to the book “Total Solar Eclipse of 2017 August 21.”  This might be a handy reference while planning for your eclipse expedition:

Elegant eclipse maps can be found here:

The Great American Eclipse web site is here:

A graphic with data on the eclipse is here:

Never look at the eclipse except during the two-plus minutes while the Sun is safely—and completely—behind the Moon.  For the partial phases leading up to and following the total eclipse you should use proper eye protection.  Here’s a product to consider for such purposes (this is not an endorsement):

Another page with more info on additional solar eclipses:

NASA’s web site with info on the Saros eclipse cycle, which includes the August 21 eclipse, is here:

For you historians, here’s a link to info on ancient eclipses:

For instance, there was a total eclipse which started in the Middle East and crossed China, Mongolia and Japan on June 10, Year 0001.

Enjoy The Great American Eclipse!


24 Mar 2015

UCI Benchmarks

Posted by Tony Soeller. No Comments

Seeking out benchmarks is a geeky thing, true enough. But these classic brass benchmarks are remnants from the early days of the campus. I’ve found several, and Eric Puchalski of OIT found two too. Locate these benchmarks yourself with a GPS receiver using the State Plane NAD27 coordinates provided below each image.

Hover the mouse over each image to read the location description.  Click on an image to see the big picture.


N 541485.761
E 1516373.173
ELEV. 110.54
L.S. 3419


N 542034.462
E 1516572.948
ELEV. 106.23
L.S. 4856


N 542499.36
E 1516003.79
ELEV. 90.87
L.S. 3120


N 542387.66
E 1514805.54
ELEV. 78.11
L.S. 3120


N 541357.38
E 1515233.80
ELEV. 124.87
L.S. 3419


N 541016.859
E 1515544.65
ELEV. 109.78
L.S. 3419


N 542186.777
E 1513196.767
ELEV. 79.91
L.S. 3419


N 539671.83
E 1515153.55
ELEV. 232.12
VTN 38

Crawford Field

N 543339.52
E 1513379.38
ELEV. 76.71
VTN 14

6 Jun 2014

UC Irvine Points of Interest “Story Map”

Posted by Tony Soeller. No Comments

Esri offers web technology to develop Story Maps which are thematic maps that employ photographs and descriptions of locations, URLs to detailed information, and point coordinates.  The Story Map can depict a progression of events over time across a landscape, or simply show points of interesting features which have a common focus.

To demonstrate Story Maps, I constructed one for UCI with points of interest (at least, interesting to me!) on campus.  Walking around campus I found sculptures, gardens, structures with plaques, and a couple of rock outcrops and lots of fine allogenic rock specimens.  Using ArcGIS Online, photos that I acquired, and text from various plaques on campus I placed points on a map and linked them to the photos and descriptions.

You can see the product here:


If you have a story to tell with your research using geography, photographs and descriptions contact me to make your own Story Map.

5 Jun 2014

Constructing a Logarithmic Classification and Scale in ArcMap

Posted by Tony Soeller. No Comments

raster with log scale

A researcher on campus needed to depict concentrations of coliform bacteria in water using colors, for values, and a logarithmic classification.  No such logarithmic classification option exists in ArcMap.  There are several classifications (via Layer Properties > Symbology tab > Quantities > Graduated colors > Classify…) including Equal Interval, Defined Interval, Quantile, Natural Breaks, Geometrical Interval, Standard Deviation, and a Manual classification option.  Employing a logarithmic classification requires some custom work using the Manual classification.

The researcher wanted the logarithmic classification—and the classification scale—to have four cycles: 1 to 10, 10 to 100, 100 to 1,000, and 1,000 to 10,000.  Using the Manual classification, values for individual classes can be manually defined, which is necessary for the custom-built logarithmic scale.  The natural choice would be to have 9 classes for each cycle plus one more for the 10,000 class. That would be 37 classes.  In ArcMap there are up to 32 classes available for each of the classification options, including the Manual classification.  As such, 7 classes were chosen for each cycle yielding a scale bar with 28 classes.  An additional class (for a total of 29) represents the starting value of 1.  To most closely represent a true logarithmic scale, each class comprises a greater range of values than its preceding lower value.  So, for instance, between the values of 1.001 and 10.000 the seven classes do not contain an even division of values.  Rather, the lower classes comprise a smaller range of numbers (1.001 to 1.389 for instance) than the higher classes (7.198 to 10.000 for instance), as is the case for a true logarithmic scale.  The actual class break values were calculated using the formula 10^(x/7) where x represents the class number from 0 to 28.

To help build the classification and vertical scale, a simple raster was converted to a polygon feature class and two isolated polygons were assigned the values of 1 and 10,000.  The image shows the polygon feature class with two polygons in the corners colored based on their extreme values of 1 and 10,000.  The two vertical scales show the logarithm whole numbers before (left) and integer numbers after (right) editing out the intermediate numbers.  This helped clarify each logarithm cycle.

To generate the scale in ArcMap without gaps between each of the classes, the “Patches (vertically)” option was set to zero points (pts.) while using the Legend Wizard to construct the legend.

An ArcGIS layer file was generated and can be downloaded here for use in similar applications where a logarithmic classification from 1 to 10,000 is needed.

13 May 2011

GIS Resources for UCI Faculty, Staff, Graduates and Undergraduates

Posted by Tony Soeller. No Comments

So frequently do I receive requests for GIS resources at UCI that I find myself repeating, via email, the same information to faculty, staff and students on campus.  So the following is a discussion of the GIS resources available at UCI.  This blog venue for disseminating information is certainly not an attempt to keep you from contacting me about GIS.  On the contrary, use the following as a starting point and then contact me for further assistance on your GIS projects. Doing so is a major portion of my job: to help UCI faculty, staff and students with their GIS projects.

In this blog I discuss

  • our Esri software Higher Education Site License
  • the UCI-GIS maillist
  • free one-year licenses for ArcGIS software for students
  • GIS classes at UCI
  • free ArcGIS on-line training
  • attending the Esri User Conference for free


UCI has a complete Higher Education Site License for Esri software

Having an Esri site license means we can distribute ArcGIS software to anyone on campus with a Windows-based computer.  OIT manages the site license and charges an annual fee for faculty and staff to use the software.  At UCI we only distribute the highest level of ArcGIS (which is named ArcGIS/ArcInfo).  For pricing, installation instructions, and software usage details go here:



Subscribe to the UCI-GIS maillist

Information pertinent to GIS at UCI is sent to campus GIS users via the UCI-GIS maillist.  To subscribe to the list go to:



UC Irvine students can get ArcGIS for free on campus

Current UC Irvine students (only) can receive free one-year copies of ArcGIS Software on campus.  UCI students attending GIS classes on campus can request a copy of the software from their professor.  UCI students not attending a GIS class can request a copy of the software from the OIT Help Desk (OIT@uci.edu).  The software must be installed on the student’s personally-owned computer and not on a UCI-owned computer or any computer owned by a business concern.

Installing the student copy of the software is different from the procedure for installing the for-fee software indicated above.  Contact the OIT Help Desk for instructions.


GIS Classes are taught At UCI

Undergraduate GIS classes are taught by Prof. George Tita in the School of Social Ecology, and by Prof. Joe Devoy in the School of Social Sciences.


Free ArcGIS training is available to faculty, staff and students

Esri offers free online self-paced GIS training.  You attend the courses at your leisure and work through the exercises with ArcGIS running on your computer simultaneously.

To view the courses, go to


then click on Catalog > Find Training

To attend a course you must receive an invitation to the training.  Contact the OIT Help Desk (oit@uci.edu) to request access to the training courses (i.e., OIT must request an invitation for you to attend the training).

The course I recommend to new users of ArcGIS is “Learning ArcGIS Desktop (for ArcGIS 10).”  A description for this course is here:


When viewing the list of courses you will notice some indicate a fee for the course.  Through UCI’s  Esri Software Site License many of these for-fee courses are free.

Attend the annual ESRI User Conference

Esri holds an annual International User Conference at the San Diego Convention Center usually during July.  There is an associated Esri Education User Conference which overlaps with the International User Conference at the same date and location.

Details about the conferences are here:



Any UCI student can attend any one day of the International User Conference or Education User Conference for free.

We also have several complimentary passes that allow individuals from UCI to attend any or all days of the two conferences.  If you are interested in attending one or both of the conferences for two or more days, contact the OIT Help Desk (oit@uci.edu).

1 Nov 2010

Counting Fires

Posted by Tony Soeller. No Comments

Researcher Yufang Jin in UCI’s Earth System Science was interested in identifying how many fires occurred at each location where there were multi-year multiple overlapping fires.  The ArcGIS function UNION is the primary tool because it allows you to overlap multiple polygons (here each polygon represents one fire) and
then get a new set of polygons each representing a condition where there was one or more input polygons at that location. But UNION alone does not produce the desired results.  Here
is a procedure that works.

1) Run Union (ArcToolbox > Analysis Tools > Overlay > Union) on the fires feature class or feature classes that contain the polygons.

The result of Union can leave some polygons that are separated spatially yet representing the same polygon.  Actually, where that occurs they represent a multi-part polygon, just like the islands in the State of Hawaii.  The multiple parts from those polygons each came from the original fire but they have to be separated into unique polygons.  So…

2) Run Multipart To Singlepart (ArcToolbox > Data Management Tools > Features > Multipart to Singlepart) using the feature class that is the result of Union as input.

If there were any multi-part polygons after Union then you will see more polygons listed in the post-Multipart to Singlepart feature class attribute table.

3) Run Feature To Point (ArcToolbox > Data Management Tools > Features > Feature To Point) using the feature class from Step 2 as input.

VERY IMPORTANT: Be sure to check the box “Inside” so that the points that are generated will fall WITHIN their host polygons.

The result will be a bundle of points that are at the centroids of the polygons, and you will get one point for each polygon in the Union feature class.  So, some points will be coincident with other points.

The result of the Union operation in Step 1 created multiple overlapping polygons with exactly the same geometry.  For the next step you need to create a feature class that has just one polygon at each location.
Essentially you need to eliminate all the overlapping polygons.

4) Run Feature to Polygon (ArcToolbox > Data Management Tools > Features > Feature To Polygon) using the original fires feature class as input.  This will generate a new feature class with one polygon
at each location (as opposed to multiple polygons at each location that Union produces).

5) Right-click on the polygon feature class generated in Step 4 and click Joins and Relates > Join.

6) In the Join Data dialog click the top drop-down arrow and select “Join data from another layer based on spatial location.”

– Under 1. choose your new point feature class generated in Step 3.
– Under 2. choose the first option “Each polygon will be given a summary…”
– Check the “Sum” box.
– Under 3. assign the output feature class location and name.

That will produce the desired output polygon feature class.  The Count_ field in that new feature class will contain the number of fires that occurred at each polygon location.  You can then create a choropleth map and
color each polygon based on number of fires each polygon represents.

The image above—a hypothetical case of three partially overlapping fires—represents the results of this procedure.  The colors represent the number of fires at each location.  In the center, one polygon shows where the three fires overlapped.  The points represent the centroids of each polygon.  As noted in Step 3, some of the points are spatially coincident.

9 Sep 2009

Station Fire

Posted by Tony Soeller. No Comments

Station Fire 2009

The Station fire has been raging in Los Angeles County since August 29.  ArcGIS shapefiles of the fire perimeter are provided, with generally daily updates, by the Geospatial Multi-Agency Coordination.  (On their web page, click Download Perimeters to access the shapefiles.)  I accessed the shapefiles and generated this ArcMap product which shows the oldest date of the fire perimeter in blue, and most current date in red. Dates on the map are associated with the colored polygons which, in turn, indicate how far the fire had progressed up to that date.

In an earlier post, I discussed a GIS of the Pacific Crest Trail.  I was concerned that the fire impacted the trail.  Indeed, the blue line defines the trail’s path through the burn area.

On the map, the background terrain base is provided by ESRI.  (To add that base layer to ArcMap click File > Add data from ArcGIS Online… then click on the World Terrain Base icon.)

A satellite image of the fire burn area acquired by NASA’s ASTER satellite is available here: http://earthobservatory.nasa.gov/IOTD/view.php?id=40118&src=eoa-iotd

2 Sep 2009

Pacific Crest National Scenic Trail GIS

Posted by Tony Soeller. No Comments

For some time now, my two sons and I have long been interested in hiking all or portions of the Pacific Crest Trail.  Annually, hundreds of people do so.  The Pacific Crest National Scenic trail website describes the trail.  I thought constructing a GIS of the trail would be interesting, if nothing more than to be able to view where the trail runs throughout California, Oregon and Washington.  But I did not want to digitize the entire trail myself.  One of the great things about GIS and the Internet is that there are many people out there creating GIS spatial data that you can simply import to ArcMap.  Commonly I go to Google and enter the word ‘shapefile‘ followed by the theme for which I want to acquire some GIS data.  For this project, I entered ‘shapefile Pacific Crest Trail.’  Doing so, led me to the above PCT website and a downloadable shapefile for the trail.  Thanks guys!

I brought the shapefile into ArcMap and then added several other layers of basemap data that ESRI provides (via UCI’s software site license) through their Data & Maps product.  Without too much effort, this map is the result. (If you drill into the PCT web site you’ll see an even more complete map.)

Pacific Crest Trail

We have actually hiked some portions of the trail, particularly segments passing through eastern Yosemite National Park.  I thought of highlighting those segments on the map, but they are so short relative to the entire trail length that they would be obscured on the map.  I’ll wait until I have more mileage to make an impact on the map.

1 Sep 2009

Crime Modeling

Posted by Tony Soeller. No Comments

I’ve been helping Jim Meeker (Associate Dean, Social Ecology) and Ashley Demyan (Grad. student, SE) to build an ArcGIS ModelBuilder model for analyzing community crime.  Input to the model are individual point layers, representing crime events, and an associated polygon layer, representing the community boundary.

This image shows the model.  (Click on the image to see a larger view.)

K Density Model

Notice the variable StandardDeviation as an ellipse that represents output from the Get Raster Properties function.  That variable is used as input to the CON function.  The dashed line between StandardDeviation and CON represents the dependency which CON has on the StandardDeviation variable.

Here’s output from the model for one set of inputs.

PD 2004 Significant Violence Areas

29 Aug 2009

7 Deadly Sins

Posted by Tony Soeller. No Comments

Joanne Christopherson, who teaches GIS classes in UCI’s School of Social Sciences, sent me this GIS map that was developed at Kansas State University and which depicts the “7 deadly sins” based on various community attributes including population, income, poverty, theft, violent crime, luxury expenditures, fast-food restaurant density, and STD cases.  This map was presented at the ESRI User Conference in July 2009.


Wired magazine (September 2009, page 26) got ahold of the maps and published modified versions showing the range of sin for each category from “saintly” to “devilish.”