Historically, GIS tools resided on powerful desktop machines and were accessible to highly technical staff. This paradigm has shifted through the deployment of online GIS tools that enable maps, analytical tools, and GIS capabilities to be accessed through online mapping and online GIS services. This allows non-GIS systems and to take advantage of the power of GIS, providing GIS capabilities to anyone, anywhere, at any time.
The eGIS Program maintains a variety of online GIS mapping services and Application Programming Interfaces (APIs) that developers use to build applications or automate business functions to support the wide use of GIS tools. These include:
- Map Services – Customized, high resolution maps embedded in applications, including cached and dynamic map services.
- Geocoding Services – for locating and validating addresses nationwide
- Querying services – for searching for geographic features
- Routing services – for getting direction and optimizing routes.
- Identification Services – for finding administrative districts by address
- Optimized Search Services – for rapidly returning information from big data sets.
The eGIS Program also develops, supports, and hosts departmental GIS Mapping Services.
Attachment List
| Attachment | Document Name | Description |
| B.1 | Instructions for publishing departmental map services | How departments can publish their own map services |
| B.2 | Web Services Guide | Technical Guide for using eGIS custom-built web services (for programmers) |
| B.3 | CIO Recommended Technologies for GIS | A list of technologies recommended by the CIO and the eGIS Committee for GIS infrastructure |
| B.4 | Online Map Services | A list of new/updated REST endpoints as of November 16, 2015 |
Web Services
A web service represents a GIS resource (e.g. map, geocoder) that is located on a central server and is made available to client applications and/or web browsers to consume. Publishing a web resource allows one or multiple organizations to simultaneously access and consume the resource.
Esri ArcGIS Server
ESRI’s ArcGIS Server software is the worldwide leader in deploying GIS tools via web technologies. ArcGIS Server provides geospatial services through standard communication protocols (JSON, XML, SOAP, REST) to support GIS capabilities for applications, systems, and programs.
ArcGIS Server effectively web enables the Enterprise GIS Repository – enabling the rapid development of applications for use by departments to streamline and improve their operations through the inclusion of GIS capabilities.
Most importantly, ArcGIS Server provides standard methods for accessing GIS capabilities (WMS, WFS, WMTS, etc). Once a developer understands how to leverage a single service, the developer can use the exact same techniques to access any service published through ArcGIS Server, eliminating code duplication and supporting a shared code repository.
Departmental application developers have access to a rich set of APIs, code samples, and technical resources to help them leverage the technology and services supported by the eGIS Program.
Map services
A map service connects to GIS data located on the eGIS Database Server to make maps, data, and attributes available to many types of applications. The eGIS group hosts a variety of dynamic and cached map services for County departments to consume in their web mapping applications. See Attachment B.4 for dynamic, geocode, and cache map services developed by the eGIS Group.
Cached Map Services
Cached map services serve maps very quickly using a cache of pre-drawn static images. Returning an image tile from the cache takes the server much less time than drawing the map image on demand. Access to the features and data contained in the map is maintained. Generally cached map services underlay dynamic map services to provide a context for the information shown in a map. The Google Map that everyone is familiar with is an example of a cached map service.
Cached map services maintained by the eGIS Program are accessible from http://cache.gis.lacounty.gov/cache/rest/services/LACounty_Cache and include:
- LACounty_Parcel – Parcel Map and accompanying attributes such site address, property size, and year built.
- LACounty_Parcel_OwnershipSecure (requires login) – Parcel Map and accompanying attributes that includes ownership and mailing address as well as the attributes available in LACounty_Parcel service.
- LACounty_Aerial_<Year> – Imagery Base maps (2002, 2006, 2008, 2011, 2012, 2013, and 2014 aerial photography)
- LACounty_Aerial_2006_Infrared – Color Infrared (CIR) Imagery from 2006 aerial photography
- LACounty_Streetmap – Street basemap which contains street labels, tree canopy, building outlines, addresses, etc.
- LACounty_Base – Combined imagery and labelled streets.
- LACounty_Canvas – A lighter version of the Street basemap which is optimized for overlays of Dynamic Map Services.
- LACounty_Landbase – A basemap with detailed annotation
Dynamic Map Services
Dynamic map services are displayed in the application when a request is made to the server. As the user pans around in the mapping application, the service requests new map images from the server to display. The eGIS Program maintains dynamic map services for many authoritative layers for inclusion in applications and are accessible from http://arcgis.gis.lacounty.gov/arcgis/rest/services/LACounty_Dynamic. These map services follow the same organizational structure as the Enterprise GIS Database Server databases, with the following services:
- Administrative Boundaries – County’s key administrative boundaries such as Service Planning Areas and Health District are available.
- Basemaps and Grids – US National Grids and Township Ranges and Section Rancho Boundaries are available.
- Demographics – Census Data from 2010 Census, Census Geographies from 2000 and 1990 are available.
- Elevation – Contours, Hillshade, Digital Elevation Model, and Digital Surface Model are available.
- Hazards – Fire hazards, earthquake hazards, and flood hazards related data are available.
- Hydrology – Points, lakes, streams/rivers, and watershed boundaries are available.
- LMS_Data_Public_2014 (Points of Interest) – Publicly available points of interests
- LMS_Data_FOUO_2014 (Points of Interest) – Points of interests For Official Use Only
- Political Boundaries – LA County Supervisorial District, Congressional District, CA State Assembly District, CA State Senate District, Board of Equalization, and LA City Council Districts are available. Some have historical district boundaries.
- Redistricting Data_2011 – Detailed demographic dataset that was used for 2011 Redistricting.
- Street Labels – Street label map services for the purpose of cartographic overlay
Transportation – Contains milepost markers and disaster routes
Departmental Map Services
For departmental applications, departments are able to create and publish their own dynamic map services to a dedicated folder on the GIS Server. Instructions for doing that are included in Attachment B.1. Departmental map services is accessible from http://arcgis.gis.lacounty.gov/arcgis/rest/services/<Department>.
Geocode services
Geocoding services translate an address or landmark into a coordinate that can be placed on a map. The County’s geocoding services connect to the Countywide Address Management System (CAMS) to find the locations of clients, incidents, infrastructure, and any other address stored in a County system. County departments maintain millions of records with addresses in them – a geocode service geospatially enables that information to be mapped, analyzed, and compared with other information.
Geocode services are available from http://geocode.gis.lacounty.gov/geocode/rest/services.
The Enterprise GIS Program maintains two geocoders (aka Locators)
- CAMS_Locator – Searches for addresses in the County only. It leverages the data maintained in Countywide Address Management Systems (CAMS) and is updated every week.
- CAMS_Locator_Nationwide – In addition to CAMS_Locator, this locator searches one more layer of data that covers nationwide. The geographic area of LA County is updated every week while the remainder of the area remains static.
Other Uses
Geocoding services can be used to:
- Validate Addresses – to determine if addresses exist before they are entered into County systems.
- Clean up addresses – fixing addresses that have incorrect information
- Reverse geocode – take coordinates and find the relevant address.
- Unduplicate data – finding two client records in the same location may well show duplicate information.
- Detect fraud – multiple payments going to the same location with different names may show fraud.
Utilities services
Utilities services are out-of-box services that come with Esri ArcGIS for Server product. The services include Geometry service, Printing service, and Search service, where the applications can leverage the capabilities.
Utilities services are accessible from http://arcgis.gis.lacounty.gov/arcgis.
Query and Identification Services
Each map service also enables a query and search service that enables applications to query and search the data that is included in the service, returning information geographically on a map.
Identification services take a coordinate, often returned from a geocode, to find the information contains in another GIS layer. These services are critical for County departments, since they provide the foundation for providing service location information to County staff and County constituents. For example, an identification service is used to identify a County office or Board members that are responsible for 500 W Temple Street, Los Angeles, CA or to find the nearest fire station to 350 S. Figueroa Street, Los Angeles, CA.
Routing Services
Routing services provide driving directions from one point to another, including drive times and distances. The County Mileage Authorization & Reimbursement System (MARS) leverages a routing service from Google (part of the eGIS Program) to make the submission of mileage claim forms easier and faster, saving thousands of hours of County staff time.
Routing services can also support more advanced capabilities, including determining the most efficient route for many stops (like the route of a caregiver or mail carrier), or a logistics exercise, determining the most efficient combination of routes for multiple staff going to multiple locations (like UPS trucks for example).
Security
ArcGIS Server enables map services to be open or secure, supporting token-based authentication to ensure that confidential or private data is available only to users with the relevant passwords.
Optimized Search Services (Geocortex Instant Search)
Latitude Geographics Geocortex (see eGIS Applications for more details) Instant Search technology supports a highly scalable and extremely fast indexed search engine that provides a fast and intuitive search across millions of features and associated records. This feature allows end users to see search suggestions as they are typing what they are looking for (AIN of parcels, cities and communities, Points of Interests). As soon as the user enters three characters, a list will immediately appear to suggest, hint, or predict, what the user is searching for. A maximum of ten selections will appear. The user may continue typing in the characters if the entry is not there and the Instant Search feature will continue to give suggestions.
The source for the Instant Search comes from the map services that the eGIS group or departments publish onto the eGIS servers. Any map service can be indexed and included in the Instant Search.
Custom GIS web services
The eGIS group has developed customized GIS web services that involve geocoding, routing, and identifying. These extend the Esri web services to provide specific functionality for County business processes enabling faster programming and deployment for eGIS departments.
Current web services support:
-
- Geocoding
- Finding district and administrative boundaries from addresses
- Finding parcel information from addresses
Detailed specifications for developers are included in Attachment B.2 – Web Services Guide.
The Geocode function is designed for applications that require a single matched address (generally automated computer to computer communication), compared to the GeocodeFindCandidates function which returns a list of possible matches and which should be used for application developed. In fact, this service returns the first result from the GeocodeFindCandidates service. LA County reference files are extremely accurate and in most cases will provide the correct result, but in some cases, two candidates will have the same score, and this service will select only one. See the Web Services Guide for technical description and examples of the Geocode and GeocodeFindCandidates web services.
The Identify web service contains two sets with different goals. The first set has two services that will return a list of the most commonly requested political districts including:
-
-
- City or Community Name
- Supervisorial
- Congressional
- State Senate
- State Assembly
- State Board of Equalization
-
The second set of Identify web services covers a number of functions developed to perform a basic function of Geographic Information Systems – “where am I?” Each function takes the input parameter, a set of coordinates, and returns a single field/value pair with information about a boundary they are inside. For example, the GetZipcodeFromXY function returns the zipcode, the GetSPAfromXY returns the SPA (Service Planning Area).
These functions rely on a generalized back-end function called GenericIdentify which allows new functions to be implemented very quickly upon request. The functions have been designed so that code does not need to be changed on both our servers and required minimal change for developers since ALL response tags are the exactly the same. If you need a specific function, contact the ISD Enterprise GIS Team.
GIS Web API and GIS Application Development
Web Services are only as useful as how they support application development. The Online Mapping Services the eGIS Program provides can be used by widely adopted Application Programming Interfaces (APIs), making application development easier, faster, less expensive, reusable, and interoperable. The Enterprise GIS Steering Committee has developed a number of CIO Preferred Technologies for GIS, which can help department select the technology they will use for application development. This document is included as Attachment B.3
Esri Development Tools
Esri maintains a large library of APIs, Software Development Kits (SDKs), and tools that enable programmers to leverage the County’s GIS Mapping Services right away. Replacing their sample map services with the County’s map services is easy to do and enables departments to begin application development rapidly.
The Esri Developer page is here: https://developers.arcgis.com/en/
Leaflet
For lightweight and mobile applications, Leaflet (http://leafletjs.com/) has distinguished itself as a simple and powerful library for building simple applications, especially on a mobile platform. It can leverage both external basemaps from MapBox, Esri, and Google, as well as internal map services. A number of commercial sites leverage leaflet, which is a valuable addition to the GIS development space.
Geocortex
Additionally, the eGIS Program maintains an enterprise license with Latitude Geographics for the Geocortex Application Development Framework (more in the next section).
Service Level
The Enterprise GIS Group maintains a Service Level Agreement (SLA), which outlines the service levels, roles and responsibilities, a staff matrix, escalation procedures, and terms and conditions governing the use of and access to eGIS systems.
Details about the eGIS Online Mapping Service Levels and staff responsibility matrix can be found in the relevant section in the SLA.