Monthly Archives: October 2011
ArcGIS Online World Topographic Map updates for October
The ArcGIS Online World Topographic Map (World_Topo_Map) was recently updated with several more contributions from the user community.
Albertov Campus, Prague, Czech Republic, at 2K
Managing layer visibility and selections
Managing layer visibility and selections with the table of contents’ List By Visibility mode
The table of contents in ArcGIS 10 has several ways of listing the layers in the map: by drawing order, source location of the data, whether layers are visible, and whether layers are selectable. A particular list type may be more useful than others depending on the current mapping task. For example, List By Drawing Order is best at setting which layers draw on top of others and List By Source works well to help repair broken data links for layers from different workspaces. In an earlier post, I focused on the table of contents’ List By Selectable mode when I wrote about refining the selected features while editing. In this post, I am going to show how I can use List By Visibility to manage layer visibility and selections.
Design principles for cartography
By Aileen Buckley, Mapping Center Lead
Cartographers apply many design principles when compiling their maps and constructing page layouts. Five of the main design principles are legibility, visual contrast, figure-ground, hierarchical organization, and balance. Together these form a system for seeing and understanding the relative importance of the content in the map and on the page. Without these, map-based communication will fail. Together visual contrast and legibility provide the basis for seeing the contents on the map. Figure-ground, hierarchical organization, and balance lead the map reader through the contents to determine the importance of things and ultimately find patterns.
Blog Series – Importing and Using Your Own Data in Business Analyst – (3 of 6) Creating a Custom Report with Custom Data (Part B)
by Jeff Hincy
This is Part B of the third entry of a six part product team blog series that will walk you through importing your custom data and exposing it in multiple aspects of Business Analyst – such as maps, reports, analysis, and applications. The upcoming entries will highlight some great tips and tricks for all things Business Analyst customization. Check out the previous post here.
In Part A I focused on building a report utilizing the custom data created in a previous blog with Business Analyst Desktop. In Part B I will show you how to install the report report and run it.
Now that we have a custom report built the next step is to Continue reading
SSURGO Soils Tools: Part 2
We added a new tool for summarizing classified data to our SSURGO toolbox. The SSURGO Component Classified tool takes a categorical field in the SSURGO component table and produces an output table summarizing the proportion of each category in the field for each map unit.
The SSURGO Tools version 2.0 toolbox is available in the Esri Hydro Resource Center and the Soils Atlas Group on ArcGIS.com.
In SSURGO Soils Tools Part 1, we discussed how values contained in the SSURGO component table could be mapped by flattening the many-to-one relationship between records in the component table and the map unit polygons using a weighted average approach. However, many useful fields in the component table contain categorical data. For example, the component table field hydricrating has values of yes, no, unranked, and not prime. Since each map unit polygon has one or more records in the component table, the components must be aggregated to produce a map. The Component Classified Tool aggregates the data by summing the proportion of each class for all the components in each map unit. To produce a map, the output table from this tool is joined to the map unit polygons using the mukey field and symbolized.
Like the weighted average tool, the SSURGO component classified tool takes three inputs:
- A list of component table fields to process separated by semicolons
- A path to a geodatabase containing two tables – “component” and “mapunit”
- A path to an output folder or geodatabase
For each field in the input field list, the script creates an output table using the field’s name as the output table name and adds a field to the table to store the mukey which is later used to join to the map unit polygons and a no data field to store the proportion of the map unit with no data in the selected field. The script reads through the field and creates a list of unique values and adds a field in the output table for each unique value.
Note that if more than 20 unique values are detected the script will abort the current field and begin processing the next field in the list. This value can be changed by modifying the maxLen value in line 127 of the script.
Once the output table has been set up, the script cycles through each record in the map unit table, selects all the component table records associated with that map unit, and sums the proportion of each value in the component table field for the map unit. The summed proportion of each value is then written to the appropriate field in the output table.
Figure 1: Example of output table.
The output from this tool can be mapped in a number of ways. In this example we can join the output table to the map unit polygons and symbolize areas by the proportion of prime farmland with hydric soils (hydricrating = “yes”).
Figure 2: Hydric soils in the Sacramento, California area.
The Classifed and weighted average tools can be downloaded from the Hydro Resource Center Script Gallery or the ArcGIS.com Soil Atlas Group.
For more information, comments, and to share ideas contact Richard Nauman (RNauman@esri.com) or Michael Dangermond (MDangermond@esri.com).
Community Analyst Success Stories
by Donna Buhr
Have you had an opportunity to readany of the Community Analyst Success Stories and the innovative ways that users are finding to analyze data and create valuable insight into their communities? I like the user story, “Transparent Communication Keeps Contributions Coming”, telling how Direct Relief International (DRI), a nonprofit organization located in Santa Barbara, California, is implementing Community Analyst as a cost-efficient solution to help target potential donors.
Andrew Schroeder, Director of Research and Analysis for DRI, said, “As a lean nonprofit, we can’t spend a lot of money on a market research firm to help us find donors, so we need much better tools and intelligence internal to our organizations.”Schroeder explains, “By understanding our existing donors and finding more like them, we can attract a substantial and sustainable significant donor base. We’ll be more able to think strategically about how to raise resources.” It is really an interesting story, so you should definitely read “the rest of the story”.
Community Analyst provides you with everything you need in one easy to use application to make your own success story. Here is a link to read the full story on DRI, and how others are using Community Analyst to solve their own unique problems.Esri Community Analyst | Success Stories
We never get tired of hearing these user stories, so please let us know your Community Analyst success story.
Blog Series – Importing and Using Your Own Data in Business Analyst – (3 of 6) Creating a Custom Report with Custom Data (Part A)
by Jeff Hincy
This is the third entry of a six part product team blog series that will walk you through importing your custom data and exposing it in multiple aspects of Business Analyst – such as maps, reports, analysis, and applications.The upcoming entries will highlight some great tips and tricks for all things Business Analyst customization. Check out the previous post here.
In this entry I will focus on building a report utilizing the custom data created in the first blog with Business Analyst desktop.
We have seen how to take custom data and transform it into a Business Analyst Datasource (BDS) and how to take that data and analyze it using the tools in Business Analyst Desktop to better understand and visualize the data. Now I am going to show you Continue reading
Overviews and pyramids: Part 1 of 2, What are they and why do I need them?
This is part 1 in a 2-part blog. Part 1 provides an overview of pyramids and overviews. Part 2 will provide you with some guidance on generating them when creating a mosaic dataset.
Basically—overviews are not pyramids and pyramids are not overviews. But pyramids generated by ArcGIS have an .ovr extension (short for overview)…Wait, did I just write that?
Yes, the storage format for a pyramid is an .ovr file. But please don’t confuse this with overviews. Fortunately, overviews are organized in a folder named *.overviews. Both are similar but pyramids are created for raster datasets and overviews are created for mosaic datasets.
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|
Pyramids |
Overviews |
Description |
Lower resolution (downsampled) images of the original data. |
|
Purpose |
Improve display speed and performance. |
|
Created for |
Raster datasets |
Mosaic datasets |
Format |
Writes .ovr files—with a few exceptions. |
Writes as .tif files. |
Reads pyramids stored externally as *.ovr or *.rrd or internally (e.g. MrSID) |
||
Storage |
In a single file that generally resides next to the source raster dataset and using the same name. |
By default, in a folder next to the geodatabase with a *.overviews extension, or internally for ArcSDE.Storage location is customizable. |
Storage size |
2 to 10% (compared to original raster datasets) |
|
Downsampling factor |
2 |
3 (default) |
Extent |
|
|
Options when building |
|
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Why are you generating them?
Pyramids aren’t mandatory—but without them, the display speed of your raster dataset can be prohibitively slow, especially if the datasets are very large.
Overviews aren’t mandatory—but they are highly recommended. You do not have to create them or you can generate them in only particular parts of the mosaic dataset, such as a highly visited part of the imagery. However, if you don’t create them you may not see any imagery (you may see a wireframe instead or gray images), since there is a limit to the number of rasters that will be processed at one time (which you can change). Without them, the mosaic dataset may display slowly because of all the processing.
How to create pyramids
If a raster dataset doesn’t have pyramids, then you will often be prompted to create them when you display the data in an ArcGIS application, such as ArcMap. But it’s better to create them before you use the data. Pyramids can be created using geoprocessing tools. There are a few tool choices, since it depends on whether you have one or many datasets to process. To learn about these, see Building pyramids using geoprocessing tools. You can change the properties of the pyramids, such as the resampling method and compression via the geoprocessing environments.
How to create overviews
To create overviews, first they are defined, then generated. When they are defined, the application analyzes the mosaic dataset and using the parameters set for the overviews it defines how many are needed, at what levels, and where. Then they are added as items in the mosaic dataset which appear as new rows in the attribute table. At this point, only the rows have been created to identify the properties and number of the overviews. Next, the overview files are generated. Both defining and generating can be done with one tool—Build Overviews. However, if you need to modify any properties, such as defining a new output location or tile size, then you must run Define Overvews first (to define the properties and add the items to the attribute table), then run Build Overviews to generate the overview files.
When you do generate them, the mosaic dataset keeps track of any changes made to it, such as updating an image, adding or removing images, or altering the footprints. By running the Build Overviews tool or Synchronize Mosaic Dataset tool, with the appropriate options, the overviews will be updated.
Associated blogs
- Oh where oh where have my pyramid files gone?
- Pyramids and overviews, or pyramids or overviews?
- Take a look at raster compression, pyramids, time, and space
Submitted by: Melanie Harlow
ArcGIS API for iOS v2.1 now available
We are happy to announce that v2.1 of ArcGIS API for iOS (henceforth referred to as ArcGIS Runtime SDK for iOS) is now available.
This release builds on the support for iOS 5 provided by v2.0.1 and includes additional functionality such as -
- Ability to view map content using ArcGIS 10.1 tile packages (*.tpk files) even when the device is offline.
- New GPS auto panning modes for vehicle navigation and compass navigation
- Flexible callout positioning
- Ability to rotate the map
- ..and much more
You can refer to the documentation for more information about what’s new at v2.1 and how to migrate your existing applications.
Contributed by Divesh Goyal of the ArcGIS for iOS Development Team
ArcGIS for Android v1.0 Released
We are proud to announce the initial release of ArcGIS on the Android platform. You can install it from the Android Market now. More information provided by the ArcGIS Mobile Blog.
