December 2014
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Presentations from GIS Day 2014

If you missed a presentation and wanted to go see the slides, we have loaded the presentations that we have received from our presenters into a dedicated page.

Click here to go to the page

Thank you everyone who attended and presented

How Medieval Maps became accurate

portolan-chart-featuresThanks to Richard Ledesma for passing this along:

One of the most remarkable and mysterious technical advances in the history of the world is written on the hide of a 13th-century calf. Inked into the vellum is a chart of the Mediterranean so accurate that ships today could navigate with it. Most earlier maps that included the region were not intended for navigation and were so imprecise that they are virtually unrecognizable to the modern eye.

Continue reading here …

GIS Case Study – 2010 Local Update of Census Addresses (LUCA)

2010 Local Update of Census Addresses (LUCA)

Chief Executive Office (CEO), Urban Research Group

This slideshow requires JavaScript.

Problem: The County of Los Angeles provides services to the residents of the County.  Many programs are supported by federal funding that is calculated by the number of residents of the County.  The County is supporting the goal of the Census Bureau to find and count all County residents in the 2010 Census.
Solution:The County LUCA program worked with 87 cities and identified over 149,000 residences that the Census Bureau did not know about.  This represents an estimated 440,000 additional residents of the County, and $115 million per year in additional federal funding countywide.
Summary:Every ten years, the U.S. Census Bureau (Bureau) prepares for the Decennial Census by preparing a Master Address File (MAF) of residences to which it will mail a Census questionnaire.  The Bureau sent to the County Urban Research a CD containing 3.5 million residences with a simple question: which ones are missing?Working with 87 Cities, Urban Research created a list of every address it could document, including 7,000 inhabited Zoning Enforcement cases, and address matched (geocoded) the list to Census Tract and Block, individually connecting each matched address to those in the MAF.  Special efforts were made to capture all Group Quarters, defined as where unrelated people live together (college dorms, prisons, camps, convalescent hospitals), mobile home parks, and especially, unpermitted residences from Cities’ Zoning Enforcement files.

Some examples of what was found during this effort:

  • 990 group quarters (20% more than the original 4,000)
  • 50 unlicensed mobile home parks
  • 6,000 mobile homes not in the Assessor file
  • The City of San Fernando reported 4,500 residences and an additional 1,200 inhabited garages, a 28% increase.

The County reported 149,000 new residences to the Bureau that were not in MAF; the Bureau accepted 143,000 of them (96%).

We estimated that 3 persons live in each per residence – that is like finding a City of 440,000 people (slightly less than the City of Long Beach).  The City of Los Angeles calculates that a counted person is worth about $269 per year for ten years.  Using these numbers yields a very large potential revenue recovery of over $115 million per year of State and Federal funds to 87 Cities from a five-month project costing $250,000.

Contact:  Victor Chen,

(562) 658-1799


December Enterprise GIS Committee Meeting – Agenda

The agenda for tomorrow’s meeting is here: December 2014.eGIS meeting notice and Agenda

We’ll go over lessons learned from GIS Day, and discuss updates from the reclassification exams, among others.

See you tomorrow!

GIS Case Studies

LA County has created a number of case studies for the benefits of GIS.  In order to broaden their reach, I will be publishing these as individual posts over the next few weeks – approximately on each week until we run out :).  This will make them more searchable online since the major search engines crawl the posts better than they crawl the documents in this site.

If you want to get a jump start on them, you can access them by clicking this link.

There are other documents like this on this site in the Enterprise GIS Committee documents page.

GIS Case Study – LA County Solar Map

LA County Solar Map and Green Planning Tool

Chief Information Office with Internal Services Department

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Solar photovoltaic electricity deployment has been slowed in LA County, and elsewhere, due to the complexities of the installation process.  A business or resident interested in solar is effectively on their own as they attempt to wade through information such as: their solar electricity potential, installation costs, tax rebates, estimating energy savings, finding reputable installation contractors, and performing return on investment (ROI) calculations.


The Los Angeles County Solar Map ( is a regional internet portal where LA County residents can easily find information about the potential of installing solar photovoltaic (PV) on their home or business.  By typing in an address, residents and businesses are shown:

  • Their total roof area and roof area suitable for solar
  • The system size they can install and the amount of electricity they can generate
  • The cost savings per year
  • The carbon dioxide savings per year
  • Links to installers, rebate programs, and cost estimates.

The decision to install a solar energy system is generally difficult because it involves complex factors such as: the solar electricity potential (based on geography and building characteristics), installation costs, availability of rebates, estimated energy savings, identifying reputable installation contractors, performing return on investment (ROI) calculations, and who to contact to get started.

The County’s Chief Information Office teamed with the Internal Services Department to find a solution and created a Countywide Solar Map that benefits all buildings in Los Angeles County.  In L.A. County there are 3.5 million single-family residences and hundreds of thousands of non-residential buildings that are in the Solar Map database.

The Solar Map has been met with great enthusiasm since its launch in April 2009, averaging close to 100 visitors per day.  It is being leveraged by the County as a tool for evaluating the feasibility of installing solar PV on County buildings and in County properties, and the Gas Company has worked with the County to add solar water heating information to further enhance the site.

The application is used by County departments to identify candidate County buildings and properties for solar installations to meet a goal of offsetting 1% of its annual energy consumption with solar power.    The County has realized direct cost savings by eliminating the need to send engineers or contractors on to the roof of each of the 1,000 buildings it owns to complete a solar analysis.

The Solar Map has saved other solar stakeholders (utilities, cities, contractors, solar installers and homeowners) millions of dollars by reducing the time and risk necessary to evaluate potential projects.

Contact:  Mark Greninger, Geographic Information Officers


(213) 253-5624

Census Bureau releases new 5-year American Community Survey Data

census_explorerThe ACS dataset for the past 5 years has been released by the Census Bureary.  See the press release

As well, there are a number of mapping applications that use this data.  Take a look!

Census Explorer: Young Adults: Then and Now Edition

Do more young adults today in your area live with their parents than in previous decades? Do more own their own homes? This edition looks at multiple characteristics of the population age 18-34 in 1980, 1990, 2000 and today (using 2013 American Community Survey 5-year data). Zoom in to see tract, county, metro, state and national-level data.

Continue reading Census Bureau releases new 5-year American Community Survey Data

LA County GIS Viewer- Elevation Profile tool now available

profile_results_smallAn elevation profile shows the change in elevation over distance, and can be a powerful way to learn about how steep a hillside is, how difficult a terrain is to traverse, show expected water run-off, and helps visualize elevation information for many business needs.


In partnership with Latitude Geographics, LA County is happy to release an elevation profile tool as part of the LA County GIS Viewer that uses the highest resolution data available, the 2006 LARIAC 5-foot Digital Elevation Model (click here for details about that dataset).


How to access the elevation profile tool

In the GIS Viewer, the elevation profile tool is located on the right side in the Measurement Tools Tab (see picture below)







Follow the instructions provided and the elevation profile will be calculated on the fly.  You can mouse over the profile and see the corresponding location on the map.

LA County GIS Viewer adds 2014 LARIAC Imagery

Starting January 2014, the Los Angeles Regional Imagery Acquisition Consortium (LARIAC) – click here for more details – funded the acquisition of updated 4-inch resolution orthogonal imagery.  A preliminary dataset has been delivered to the County, and it is now available in the LA County GIS Viewer.

Note – 2014 was a VERY dry winter, so the imagery will naturally appear brown compared to earlier imagery.

Important – this is a preliminary delivery, so you will see seamlines, wavy features, and other issues.  During the processing of this imagery, some tiles at some levels failed to draw and show as blue rectangles in the image.

GIS Service Offerings from the State of California

For cities and agencies that want to use GIS, but don’t want to spend huge amounts of money, the State GIO, Scott Gregory, is putting the state’s GIS resources at your fingertips.

The state will support geocoding, map service hosting, and GIS application hosting, each for $1,200/month.  No software to buy or license.

Click on the link to view the full document: California Department of Technology – GIS ServicesDescription and Pricing