Each polygon contains a 8 digit number [...]]]> This dataset contains the dates of the imagery compiled into the 2011 Los Angeles Regional Imagery Acquisition Consortium 4-inch and 1-foot color orthophotography.  We are currently waiting for one final block to be added to this dataset (the National Forest north of Santa Clarita).

Each polygon contains a 8 digit number that corresponds to the date the image was acquired.  Over 350,000 individual image chips were merged to create a seamless orthophoto across the County of Los Angeles.  This dataset will enable participants and other entities to know  the date the image was acquired.

Processing History

This dataset was extracted from a larger polygon file (with 105,000 polygons) which contained the boundaries of the individual image chips that were merged into the final LAR-IAC product.  In order to reduce the size of the file, the boundaries were smoothed using the ArcMap generalize command to reduce the number of vertices, which reduces the file size while not dramatically impacting accuracy.

Samples

Download the data

• lariac3_dateflown.zip (22 Mb zipped shapefile that includes a layer file to help with symbology)
• LARIAC 3 Date Flown (2011).lyr (For County staff only – layer file that connects directly to the Enterprise GIS repository to show the data)

CAMS Data (October 2011)

Current data date: August 2012 – we will be releasing new versions of this data periodically.

Important note: This file is not final – it is an intermediate step and should be used with the understanding that further work is being performed.

Description

The LA County Street Center TIGER [...]]]>

CAMS Data (October 2011)

Current data date: August 2012 – we will be releasing new versions of this data periodically.

Important note: This file is not final – it is an intermediate step and should be used with the understanding that further work is being performed.

Description

The LA County Street Center TIGER road file is a street centerline network in development by Los Angeles County to move toward a public domain street centerline and addess file.  This dataset can be used for two purposes:

1. Geocoding addresses in LA County – this file currently geocodes > 99.5% of the addresses in our test files (5,000 out of 8 million addresses) using the County’s geocoding engines.
1. This last statement is important - the County splits the street names and addresses differently than most geocoders.  This means that you cannot just use this dataset with the standard ESRI geocoding (US Streets) geocoding engine.  You can standardize the data to resolve this, and we will be publishing the related geocoding rules and engines along with instructions on how to use them, in the near future.  Please review the data fields to understand this information.
2. Mapping street centerlines in LA County – note that the street types in this file are not fully updated yet.  Use with caution.

History

LA County has historically licensed the Thomas Brothers Street Centerline file, and over the past 10 years has made close to 50,000 changes to that file.  In order to provide better opportunities for collaboration and sharing among government entities in LA County, we have embarked upon an ambitious project to leverage the 2010 TIGER roads file as provided by the Census Bureau and upgrade it to the same spatial and attribute accuracy as the current files we use.  This effort is part of the Countywide Address Management System (click the link for details).

Processes

The County downloaded and evaluated the 2010 TIGER file (more information on that file, including download, is at this link).  The evaluation showed that the TIGER road file was the best candidate to serve as a starting point for our transition.

Since that time, the County is moving down a path toward a complete transition to an updated version of that file.  Here are the steps that have been completed and are anticipated.

1. Upgrade the geocoding accuracy to meet the current LA County street file licensed from Thomas Brothers.  This has been completed by the Registrar/Recorder (RRCC) – matching rate have improved dramatically. COMPLETE
2. Develop a countywide street type code to reflect various street types we use.  We have used various sources, including the Census CFCC and MTFCC codes to develop this coding.  The final draft is here –  Final Draft of Street Type Codes for CAMS (excel file)
3. Update the street type information to support high-quality cartography.  IN PROGRESS - we have completed an automated assignment for this, but RRCC will be manually checking all street segments in the County to confirm.
4. Load this dataset into our currrent management system and begin continuing maintenance.

 Samples (click to enlarge)

1971

1981

1991

The data from 1991 was provided by the Registrar/Recorder.

The data from 1971 and 1981 was digitized from scanned and rectified County Engineer maps provided by [...]]]> Supervisorial District Boundaries for LA County for 1971, 1981, and 1991.

Samples (click to enlarge)
1971	1981	1991

The data from 1991 was provided by the Registrar/Recorder.

The data from 1971 and 1981 was digitized from scanned and rectified County Engineer maps provided by the Department of Public Works.

1. Download the Ortho rectified 1971 County Engineer’s Map (zipped geo-tiff)
2. Download the Ortho rectified 1981 County Engineer’s Map (zipped geo-tiff)

Engineer Maps (click to Enlage)
1971 Map	1981 Map

Download/Access the GIS Data

Each of the files below contains all three supervisorial district boundaries in one file

• Historical Supervisorial Districts (ArcGIS 10 Layer File) - For LA County staff with direct access to the Enterprise GIS Repository.
• historic_supervisorial_districts (zipped shapefiles).

This dataset comes from the County’s Location Management System (LMS), which is a collaborative system to locations across the County. The full dataset contains over 66,000 locations, including 42,000 public (available for download below) and14,000 non-public locations (available for government entities only) with consistent attributes. Location types are broken [...]]]> Last Update: January 2013

This dataset comes from the County’s Location Management System (LMS), which is a collaborative system to locations across the County.  The full dataset contains over 66,000 locations, including 42,000 public (available for download below) and14,000 non-public locations (available for government entities only) with  consistent attributes.   Location types are broken into more than 270 unique types using three categories (cat1, cat2, cat3) that provide detailed breakdowns of the location types.

We need your help keeping this data up to date

The County has launched an ambitious program to maintain this data collaboratively.  Each location in the dataset has a defined page for it – stored in the link field.  If information is incorrect, out of date, or the location is wrong, you can click on the link in ArcMap (an identified point will have a hyperlink icon next to it) and you will be taken to the page in the LMS for that location.  A registered user can provide comments for that location, which will be sent automatically to the location owner.

If you feel that you are the authoritative owner for one or more of the categories or points, please contact me (email below).  Please read the LMS Introduction and Documentation

Information contained in the LMS Data

This dataset is the single, central repository for locations of interest to government, including basic information about those locations.  So we will keep heliports in our dataset, but not dry cleaners.

Information includes: Parks, campgrounds, trails, churches, colleges and universities, public and private schools, hospitals, mental health centers, physical features like valleys from the USGS GNIS, Manufacturing Locations, sheriff and police stations, fire stations, social service locations, child welfare service locations, airports, etc.

To download an Excel table showing the full set of Categories, download: Location Categories (includes use constraints and data owners).xlsx

Data was compiled from the following data sources:

• 211 LA County: http://211lacounty.org/
• HSIP Freedom from the HIFLD working group: http://www.hifldwg.org/ – some of this data is for official use only and cannot be downloaded here.  Authorized users should contact me to access this data.
• County Services Locator: http://maps.lacounty.gov/location/search
• Other GIS files.

Download the data

• lms_data_public_201301 (zipped shapefile) - Data as of January 2013. This is the public data version only (no data that has been tagged “For Official Use Only (FOUO)” is part of this file.

Snapshots

The Land Types dataset includes various types of land use that are critical for mapmaking and geographic analysis. The data has been created to match parcel boundaries where possible, and digitized from 4-inch aerial photography where more [...]]]> Updated December 2012 – Added the Michael D. Antonovich Open Space Preserve and the Santa Clarita Woodlands Park

The Land Types dataset includes various types of land use that are critical for mapmaking and geographic analysis.  The data has been created to match parcel boundaries where possible, and digitized from 4-inch aerial photography where more detail was needed.

Important note:  This data is still under development and is not complete as of April  2011, and it should not be used for authoritative analysis.

General land types that have been captured include:

A full listing of the categories can be found here: Land Types Categories – February 2011 (Excel Table).xlsx

This data is the result of a collaborative county project that began in January 2011 to update and take ownership of this valuable dataset.  It is closely related to the Location Management System program, which updates information represented as points.  This data is a replacement for the currently licensed Thomas Brothers OWNA layer.  It has greater scope, greater accuracy, and will be maintained collaboratively by County departments and various agencies that have true jurisdiction over the actual land types.

The LA County Department of Regional Planning has made a significant enhancement to the land types data through its development of three layers:

• Parks, Recreation Centers, and Sports Complexes – 1,340 total
• Schools – 2,951 total- see the School Update Process description (.pdf file)
• Open Spaces – from the ‘California Protected Areas Database (CPAD)’ (click here for website).

LA County’s eGIS Group developed the boundaries for 110 Golf Courses, and the LA County CIO’s office developed a number of other layers, including cemeteries, colleges, and shopping centers.

Data Access:

• Land Type Layer File (for County access only)
• land_types_2012_12 (zipped shapefile)

This height data was developed from the following two data sources:

This hillshade was computed from the 2006 Digital Elevation Model (DEM) [...]]]> A Hillshade is a  shaded relief raster from a raster. Simply, when used with maps, it provides a three-dimensional aspect to the map based upon the relief of the underlying area.  A more detailed definition of a hillshade can be found here.

This hillshade was computed from the 2006 Digital Elevation Model (DEM) acquired by the Los Angeles Regional Imagery Acquisition Consortium (LAR-IAC), and is a 5 foot by 5 foot raster grid.  This hillshade has been improved by Hwa Saup Lee of the County’s Internal Services Department to smooth the differences between the two LAR-IAC collection areas (high resolution 5 foot and low resolution 10 foot) and create a single seamless hillshade.

Samples

Countywide

Detailed View

Layer File

Hillshade (2006) – Corrected (Layer File)

This data was created through the Area Solar Radiation function in ESRI’s ArcGIS Desktop. For more details about this function, view the ESRI help file. That function creates four output files:

Legal Cities (like Los Angeles) are represented as well as communities (like Hollywood or Acton).

Communities (zipped Shapefile)

Details

May 10, 2013 – added the 2D building outlines

Models of County owned buildings in three formats (shape, multipatch, and KML).  These buildings were created for the LA County Solar Map and were used for high resolution modeling of solar potential

Downtown Area

for each building.

Coverage

Buildings for the urban/suburban areas of the County of Los Angeles developed from information captured in 2006 by the LAR-IAC program.

This dataset was developed by the County of Los Angeles Chief Information Office in support of the LA County Solar Map Application (http://solarmap.lacounty.gov).  A solar model [...]]]>

Coverage

Buildings for the urban/suburban areas of the County of Los Angeles developed from information captured in 2006 by the LAR-IAC program.

This dataset was developed by the County of Los Angeles Chief Information Office in support of the LA County Solar Map Application (http://solarmap.lacounty.gov).  A solar model based upon the high-resolution digital aerial elevation data included the tops of trees, the ground, and other features that would skew any solar results.  For example – the top of a tree appeared to the solar model to be a prime candidate for solar photovoltaic installation due to the amount of sunlight it received, but this was obviously incorrect, and some way needed to be found to focus exclusively on building tops for the purpose of the site.

The buildings were developed from the following three data sources:

1. The Digital Elevation Model (DEM) which modeled the ground surface at 5-foot intervals.  Click here for more information
2. The Digital Surface Model (DSM) which modeled the surface at 5-foot intervals, which included all features like trees and buildings. Click here for more information
3. The Color Infrared (CIR) imagery at 4-inch resolution which contains the Red and Near Infrared (NIR) Bands.  Click here for more information

Processing steps:

1. A Surface Height Model was created by subtracting the DEM from the DSM: Click here for more information
2. A Normalized Difference Vegetation Index (NDVI) model was created.  Click here for more information.  NDVI values range between -1 and 1.  Values > 0.1 are generally green vegetation, while values < 0.1 show things like buildings, streets, water and bare dirt.
3. All areas where the surface height was greater than 8 feet, and the NDVI value was < 0.1 were extracted and assigned the value 1.  This is the building layer.

Detailed Graphic view of processing steps (4.6 Mb .pdf file)

Important notes

This building layer has been validated to provide a true representation of buildings.  However, the data includes many small processing artifacts, and should not be used for authoritative measuring, roof areas, etc.

Detail

Detail with imagery