Archive for January, 2008
Creating KML Regions from ArcGIS Data Using Arc2Earth
Our previous posts on basic and advanced KML Region concepts gave you some background on how this functionality can be used allow you to stream your data in pieces instead of as a whole making it possible to deliver large datasets to the Google Earth viewer. In this post you will discover how to use Arc2Earth with your existing ArcGIS data to create these powerful features.
Arc2Earth can be used to create Google Earth Regions through the Regions tab with the Publisher version of Arc2Earth. The General Options button displays the Region Options dialog which can be used to set the fade effects and level of detail (LOD) for the region. You must also select a region level which is basically a course grain level similar to the levels of map tiles used in Google Maps or MS Virtual Earth. Each level represents an approximate map scale. The Visualize button displays a map window with the grid showing the regions for your export along with your layer data.
The Visualize window is particularly helpful in allowing you to see the extent of the Regions that will be created along with your data. The red lines displayed in the viewer indicate how your data will be regionalized. You can also dynamically reset the region level through this window to see the effect this will have on the size of the Regions. Map navigations tools are also provided.
Demonstration
Click here to see a demonstration of using Arc2Earth to export parcel and floodplain data as KML Regions.
More Information
GeoSpatial Training Services provides e-learning courses for GIS users. If you would like more information on Regions and other KML elements please see our “Mastering KML in Google Earth” e-learning course. Other related course include “Integrating ArcGIS Desktop and Google Earth“, “Introduction to the Google Maps API“, “Arc2Earth for ArcGIS Users“, and our “Google Bundle” which combines all these courses into one package at a significant discount.
Advanced KML Region Concepts (Altitude, Fade Extent, Nested Regions)
In our last post on KML Regions we covered some background information on KML Regions and the various ways in which they can be used in Google Earth to display large GIS datasets. In this post we are going cover additional Region subjects including altitude, fade extent, and nested regions.
Bounding Box
As we mentioned in our previous post, the bounding box and level of detail (LOD) are two of the basic, key concepts in creating Regions. A bounding box, defined by the <LatLongAltBox> element, describes an area of interest defined by geographic coordinates and altitudes. This element contains the child elements <north>, <south>, <east>, and <west> that define the boundaries of the Region. A Region is considered “active” or visible when the bounding box is within the display and the level of detail requirements are met.
Level of Detail
The Level of Detail (LOD) is defined with the <Lod> child element of <Region>. It defines a range, specified by <minLodPixels> and <maxLodPixels> that determines the visibility of data within a Region. This ensures that large amounts of data are only loaded when enough pixels are available to display the data adequately. When the Region takes up a relatively small percentage of the screen, the LOD allows you to specify a dataset with a lower resolution. The <Lod> value units are defined by square pixels. Data must occupy an area greater than <minLodPixels> and less than <maxLodPixels> to be visible.
There are a number of other Region concepts that you need to be familiar including altitude, fade extent, and nesting regions.
Altitude
The <LatLonAltBox> element can contain child elements which control the minimum <minAltitude> and maximum altitudes <maxAltitude> at which a Region will display. Notice in the figure below that the minimum altitude at which the Region will display is 10000 meters and the maximum altitude is 50000 meters. These child elements are containing within the <LatLonAltBox> element.
Fade Extent
By setting a fade extent for a Region, you can enable your objects to transition seamlessly from transparent to opaque, and back again. You do need to be careful when setting a fade extent for a Region because they are computationally expensive, and should only be used with vector data such as LineStrings, Polygons, and Points, but not with imagery data. Fade extents are set with the <minFadeExtent> and <maxFadeExtent> child elements of <Lod>. These are set as pixel values similar to the values you set for <minLodPixels> and <maxLodPixels>, and are used in conjunction similar to the code you see below.
The <maxFadeExtent> is used to determine the ramp from fully transparent to fully opaque when the Region is at its maximum visible size. The <minFadeExtent> element is used to determine the fade ramp when the Region is at its minimum visible size.
Nesting Regions
Regions can be nested so that smaller, increasingly finer levels of detail are shown as the user zooms in on the display. Previously loaded coarse levels of detail are gradually replaced with these more detailed Regions.
<LatLonAltBox> elements in a child Region should be wholly contained within the <LatLonAltBox> of its parent Region.
In our next post we’ll show you how to use Arc2Earth to create Regions from your ArcGIS data.
More Information
GeoSpatial Training Services provides e-learning courses for GIS users. If you would like more information on Regions and other KML elements please see our “Mastering KML in Google Earth” e-learning course. Other related course include “Integrating ArcGIS Desktop and Google Earth“, “Introduction to the Google Maps API“, “Arc2Earth for ArcGIS Users“, and our “Google Bundle” which combines all these courses into one package at a significant discount.
New Course – GIS Programming 101: Mastering Python for Geoprocessing in ArcGIS
GeoSpatial Training Services is pleased to announce the availability of a new instructor led virtual GIS course entitled “GIS Programming 101: Mastering Python for Geoprocessing in ArcGIS” scheduled for March 24th through April 18th.
This course is designed to teach the fundamental programming constructs of the Python language and how it can be integrated with ArcGIS Desktop to automate geoprocessing tasks. Course participants will be led through a series of 11 modules described below.
GIS Programming 101 Course Modules
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Getting Started with Python in ArcGIS
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The Geoprocessor ArcObjects
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Basic Python Language Features
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Obtaining Descriptive Information about ArcGIS Data
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Using Cursor Objects to Select, Edit, and Add Records to Tables and Feature Classes
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Enumeration Objects for Listing ArcGIS Data
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Integrating Python Scripts with ArcToolbox
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Geoprocessing Tools
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ArcGIS Server Tools
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Scheduling Geoprocessing Tasks
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Using Messages to Report Python Output
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Final Class Project
Course Details
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Class Size: 4 – 10 students
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Dates: March 24th – April 18th
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Cost: $667
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Discounts: 15% discounts are available in some cases
For more information or to register please contact eric at geospatialtraining.com
Our new Virtual GIS Classroom blends the best of instructor led and e-learning formats into a new instructor led web based format that allows for more interactivity between the instructor and student, and between students.
Our Internet course platform has the following features for each course:
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Audio and video lectures
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Video software demonstrations
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Supporting exercises and data
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Class forums and chats
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The ability to upload course assignments for instructor review
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Course wikis
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Supplemental reading materials
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Quizzes
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Glossaries
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Peer assessment
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Much more!
Using KML Regions to Display Large GIS Datasets in Google Earth
We’re going to deliver a series of posts over the next couple of weeks covering the use of KML Regions in Google Earth for displaying large GIS datasets. In this first post we’ll cover some basic introductory information that will give you some background information on KML Regions and the various ways in which they can be used in Google Earth.
What are Regions?
KML Regions allow you to add very large datasets to Google Earth without sacrificing performance. This functionality allows for the loading and display of data only when it falls within the display and occupies a certain portion of the screen. Typically, Regions are used to supply distinct levels of detail for your data where fine details are presented only when zoomed in far enough on the display. In the KML object model, Regions can be contained within any Feature which means Placemarks, Network Links, Overlays, and Containers. Most commonly, a Region is used to affect the visibility of Placemarks or Ground Overlays. The <Region> element defines this concept, and is composed of two important concepts including the bounding box and level of detail or LOD.
Bounding Box
A bounding box, defined by the <LatLongAltBox> element, describes an area of interest defined by geographic coordinates and altitudes. This element, similar to <LatLongBox> contains the child elements <north>, <south>, <east>, and <west> that define the geographic boundaries of the Region. In addition, the bounding box also has elements that define the minimum and maximum altitude (<minAltitude>, <maxAltitude>). A Region is considered “active” or visible when the bounding box is within the display and the level of detail requirements are met.
Level of Detail
The level of detail or LOD is defined with the <Lod> child element of <Region>. It defines a range, specified by <minLodPixels> and <maxLodPixels> that determines the visibility of data within a Region. This ensures that large amounts of data are only loaded when enough pixels are available to display the data adequately. When the Region takes up a relatively small percentage of the screen, the LOD allows you to specify a dataset with a lower resolution. The <Lod> value units are defined by square pixels. Data must occupy an area greater than <minLodPixels> and less than <maxLodPixels> to be visible.
Region Elements
Primary elements specific to Region include:
<LatLonAltBox> (required) – A bounding box that describes an area of interest defined by geographic coordinates and altitude.
<minAltitude> – Defaults to 0; specified in meters above sea level
<maxAltitude> – Defaults to 0; specified in meters above sea level
<north>, <south>, <east>, <west> – Used to specify the latitude and longitude coordinates of the bounding box
<Lod> – Abbreviated for Level of Detail. Describes the size of the projected region on the screen that is required in order for the region to be considered “active”. Composed of the following child elements:
<minLodPixels> – Measurement in screen pixels that represents the minimum limit of the visibility range for a given Region.
<maxLodPixels> – Measurement in screen pixels that represents the maximum limit of the visibility range for a given Region.
<minFadeExtent> – Distance over which the geometry fades, from fully opaque to fully transparent. Value is expressed in screen pixels and is applied at the minimum end of the LOD limits.
<maxFadeExtent> – Distance over which the geometry fades, from fully transparent to fully opaque. Value is expressed in screen pixels and is applied at the maximum end of the LOD limits.
Example
Now that we’ve covered some basic information on KML Regions you can click here to see an example (courtesy of Google). You’ll want to make sure you already have Google Earth installed. Experiment with different viewpoints and watch when the Region comes into view and out of view, depending on how much of the screen area it requires.
In upcoming posts we’ll cover some of the more advanced Region features, show you an example of how to create Regions, and discover how to use Arc2Earth to create Regions from your ArcGIS Data.
Get More Information
GeoSpatial Training Services provides e-learning courses for GIS users. If you would like more information on Regions and other KML elements please see our “Mastering KML in Google Earth” e-learning course. Other related course include “Integrating ArcGIS Desktop and Google Earth“, “Introduction to the Google Maps API“, “Arc2Earth for ArcGIS Users“, and our “Google Bundle” which combines all these courses into one package at a significant discount.
GeoSpatial Training Services – 2007 in Review, 2008 Preview
As we start our 3rd year in business, GeoSpatial Training Services would like to give you an update on where we’re going in 2008 as well as take a look at the many exciting developments that took place in 2007! 2007 was a fantastic year for GeoSpatial Training Services! Here are just some of our achievements for the year.
- Introduced the new GeoChalkboard Blog
- Earned recognition from GISCI as an Educational Achievement Credit provider
- Partnered with Keck & Wood, Inc. to develop the recently released “Using AutoCAD Data in ArcGIS” e-learning course
- Developed a custom e-learning course for Arc2Earth, LLC
- Released several new e-learning courses including
- Added many new clients
- Wrote many new “how-to” articles released on our blog.
- Taught various instructor led courses covering Google Earth, Programming in GIS, Introduction to GIS, and Advanced Analysis in GIS.
We’re looking forward to an even bigger year in 2008. Please continue reading below for some exciting new announcements about our forthcoming offerings in the next year.
Instructor Led GIS Courses on the Internet
Our new Virtual GIS Classroom blends the best of instructor led and e-learning formats into a new web based format that allows for more interactivity between the instructor and student, and between students.
Upcoming Courses
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GIS Programming 101 (Python)
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GIS Programming 102 (VB & ArcObjects)
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Google Earth Seminar
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Introduction to Google Earth
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Mastering KML in Google Earth
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Creating Dynamic Google Earth Applications
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Using Arc2Earth with ArcMap and Google Earth
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Our Internet course platform has the following features for each course:
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Audio and visual lectures
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Video software demonstrations
-
Supporting exercises and data
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Class forums and chats
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The ability to upload course assignments for instructor review
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Wikis
-
Supplemental reading materials
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Quizzes
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Glossaries
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Peer assessment
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Much more!
Benefits of e-learning through Virtual GIS Classroom
New E-Learning Courses Coming Soon
We have several new traditional (download and CD/DVD format) e-learning courses scheduled for release during 2008.
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Introduction to ArcGIS
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Creating Dynamic Google Earth Applications with Python
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Introduction to Microsoft Virtual Earth
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Raster GIS Analysis Using ESRI’s Spatial Analyst
Custom Training
GeoSpatial Training Services can provide custom GIS course development for your organization for the following needs:
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Conversion of existing instructor led training materials to virtual e-delivery format
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Preparation and delivery of custom training and support materials for instructor led or e-learning delivery
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Instructor/facilitator guides
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PowerPoint presentations for trainers
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Student workbooks and manuals
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Self paced e-learning
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Job aids, teaching aids, hand-outs, and quick reference guides
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Class exercises and assessments
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Development of training materials to support your custom off the shelf (COTS) products
Transportation Features in Google Maps
The Google Maps API has recently seen the addition of some new transportation related features including traffic overlays and driving directions. Traffic support and driving directions are both new features of the API and require the use of the v=2.x parameter. Traffic overlays are color-coded polyline data that represents traffic speeds on major highways and can be displayed for more than 30 U.S. cities. This functionality is implemented through the GTrafficOverlay class.
The GTrafficOverlay class, which implements the GOverlay interface, can be added to the Google Maps display through the GMap2.addOverlay( ) method. See the code example below for details on how this is done. In addition, the GTrafficOverlay class has two methods, hide( ) and show( ) which are used to toggle the display of traffic information.
Driving direction functionality is provided through the GDirections class and the supporting GStep and GRoute classes. GDirections is used to query for driving directions and display the results on a map and/or text panel. The returned information can include a map with polyline routes and/or textual information. Requests for directions can either be a query string or geographic coordinates.
The constructor used to create new instances of GDirections takes two optional parameters. The map parameter is used to hold the map showing driving directions, and the panel parameter is used to store textual driving directions. Once created, an instance of the GDirections object then uses the load( ) method to issue a new directions query. This query is composed of a string containing a valid directions query. See below for a code example.
There are a number of methods on GDirections that can be used to clear directions results, get the status of a directions request, get the distance of the directions request, obtain routes, and much more.
Each successful result returned by loading a directions query request returns one or more route objects representing the beginning and ending points of a street segment. GRoute objects store information about a single route in the directions result. Various methods are available on GRoute that enable you to get the starting and ending points of the route, get the distance and time of the route, and return an HTML summary of the route.
For more information on the Google Maps API please see our “Introduction to the Google Maps API” e-learning course.
Read Full Post | Make a Comment ( None so far )Google Maps E-Book
We recently updated our “Mashup Mania with Google Maps” e-book to include new functionality provided by the Google Maps API including transportation features such as traffic overlays and driving directions, integration with KML and GeoRSS formats, the addition of the terrain map control, and other new features.
Our 49 page e-book on the Google Maps API covers everything you need to know about programming Google Maps to create dynamic web mapping applications with one of the hottest mapping technologies. You will learn how to create maps, add map controls for user interactions, programmatically alter the map extent, add points of interest to the map, add custom icons, geocode addresses on the fly, read addresses from a database or XML file, and display aerial photography.
To obtain your free copy of our “Mashup Mania with Google Maps” e-book simply sign-up for our email newsletter at our website.
To obtain additional information on the Google Maps API please see our e-learning course, “Introduction to the Google Maps API“. In addition, GeoSpatial Training Services also provides a full set of Google Earth and ESRI e-learning courses. Please see our website for more details.
Terrain Data
Transportation Features
GeoChalkboard 