ArcGIS Explorer Blog : Custom Symbols

When Lightning Strikes

ArcGIS-Explorer-Team — Fri, 11 Jul 2008 15:34:00 GMT

California has already had another bad fire year with many hundreds of fires burning throughout the state, most started by lightning. Between June 21 and June 22 there were nearly 10,000 strikes (9,927 to be exact). Here's an Explorer view of the strikes during that period.

So how did we do this? Let's take a closer look...

How was the lightning strike information captured? Vaisala is company specializing in a variety of real-time detection systems and services, and has established the National Lightning Detection Network (NLDN). This nationwide sensor-based detection system tracks cloud-to-ground lightning activity across the continental US, 24 hours a day, 365 days a year. While the Bureau of Land Management once had their own detection grid, the BLM now contracts out to Vaisala, using their detection grid.

The Automated Lightning Mapping System (ALMS) extension for ArcGIS was used to download the near real time strike location information from the BLM data server. Using the extension strike information can be chosen for a particular time frame and geographic extent. The data was download via the internet in shapefile format.

In Explorer we chose File > Open > Shapefiles to add the shapefile data to our map. We wanted to symbolize the lightning strikes using our own lightning symbol. We made one using Photoshop, starting by creating a new image with square dimensions (we chose 30 pixels a side) and making sure our background was transparent. We drew our lightning bolt, then saved it as a local PNG file.

The next step was to use our new symbol for the lightning strikes. Here we've opened the Select Symbol window.

But rather than choosing one of the existing symbols, we clicked Add a Symbol and navigated to the folder that we saved our PNG from above in, and selected our custom symbol instead.

The ESRI Wildfire Management site has more information on using GIS for wildfire management, prevention, and suppression. Also see the Adding a new symbol Explorer Help topic.

(Thanks to Tom Patterson, ESRI Wildland Fire Specialist, for providing information and data)

Add Your Own Custom Point Symbols

ArcGIS-Explorer-Team — Thu, 03 Jan 2008 21:40:00 GMT

ArcGIS Explorer 440 includes a new set of cartographic point symbols, with many to choose from. These are billboarded, so will always remain upright and oriented properly, and will grow slightly when you hover over them. Create a Note, then right click the Note to edit its properties. Choose Symbols to see the entire palette:

You can add your own point symbols from local files by clicking Add a Symbol on the Select Symbol dialog. Browse for a local file, or enter a URL pointing to a symbol you want to use that is available on the Internet.

The symbol will automatically be resized and reformatted, and stored in your local symbols file. You can view the contents of your local symbols file by clicking Styles on the Select Symbol dialog.

Your local symbols style file is located at:
C:\Documents and Settings\<user_name>\Application Data\ESRI\ArcGIS Explorer\Styles

Hint: If you want to add custom point symbols to your map, and make them available to anyone you share the map with, put the symbols on an Internet accessible location, and use a URL to add them. When the next user opens your map, the custom symbols will be retrieved via the URL, and automatically added to the user's local symbols.

For more information, refer to the Help topic on adding a new symbol.

A Quick Peek at the Next Release

ArcGIS-Explorer-Team — Fri, 14 Dec 2007 17:04:00 GMT

We've been a little quiet here on the blog for the last couple of weeks. The reason? We've had our heads down working on the next release, which we're hoping to deliver very soon.

Here's a quick peek at a few of the new point symbols that will be included with this new version. In addition to the ones we'll provide, you'll be able to add your own custom symbols by choosing .jpg, .bmp, or .png files from your local drives or network, or from the Web.