Displaying images and attributes simultaneously in ArcGIS

Displaying attributes is one of common tasks for all GIS users. Until release of 9.3 two ways were possible – display attribute table and use identify window. Map tips don’t really qualify for this case since they are based on a single attribute.

Release of 9.3 has introduced a new tool – HTML Popup. This tool is available in ArcMap , ArcGlobe and ArcScene and it is used primarily to prepare map layers for delivery using ArcGIS Server or KML. This does not mean you can’t (or you shouldn’t) use it Desktop applications. HTML popup enables display of the following content types:

• Attributes
• URL
• Custom popup

For this occasion I will discuss display of the shapefile attributes in ArcMap 9.3.1 and Explorer 900. I chose shapefile because it can’t store images like feature class can with use of raster attribute. Shapefile in this example contains very basic information about 8 tallest buildings of the World. In addition to basic information like name, height, latitude and longitude an additional attribute was created. This text attribute is storing location of image for a building.

To be most efficient for display using HTML popup the map layer has to be prepared. This is just a simple extension of the process you are already doing because everything is set on properties dialog of a layer. First step is to choose fields to be included in HTML Popup. Selection is made on Fields tab from Layer Properties dialog. While choosing fields check if would be better to use field alias instead of field name. In this case field names are quite suitable and only change I made was inclusion of ‘(m)’ text for height.

Next step is populating fields for image location. In this example most of the images are stored locally on hard disk while one is displayed directly from the internet. Since I am using HTML popup tool I have to provide location for images in proper HTML syntax. This is accomplished using basic form of the HTML img tag. Populating small number of records like in this case is fairly simple and quick. In edit session type the img tag elements for first record and then copy and paste to other records and then enter or correct image location path. For larger number I would use field calculator. This makes things a little bit more complicated because of use of speech marks for image path. Here is an example of simple expression:

Using expression above images will be displayed in their full resolution. Sometimes this can be inappropriate because large images will obscure large part of map display. In such situation use optional parameters for img tag – width and height. In this example I have used these with the only image referenced from internet. Ensure your URL points to the image directly (not to the page containing an image).

After all required records are populated on Layer Properties dialog go to HTML Popup tab and first thing to do is to enable HTML popup tool. To enable it check the ‘Show content for this layer using the HTML Popup tool’ checkbox.

 

On this tab choose one of three available options:

• As a table of the visible fields
• As a URL
• As a formatted page based on an XSL template

When using first option results are displayed as shown in screenshot below.

 For finer tuning and case when fields names can be omitted activate ‘Hide field column name’ checkbox.

 

At this point you are done if you will use ArcMap only. Just use HTML Popup instead of identify tool. If you want to share the data you can create a layer package or a layer file. Layer files (and layer packages) can be used in ArcGIS Explorer 900 (AGX). Here are examples of using this layer file in AGX. Remember, layer file is created for shapefile.

Last option for HTML Popup in ArcMap is using XSL template. This option provides great flexibility to create custom XSL code. On the other side one has to be familiar with stylesheet design.
In the case if you are not you can simply copy the content of popup.xsl file from default install location -
C:\Program Files (x86)\ArcGIS\Styles\HTMLPopup directory (64bit installation). ESRI is recommending this option at the moment because stylesheet used in AGX is slightly different then one from ArcMap. This is logged as an enhancement request for next release of AGX.

Example of third option - XSL template

Another option to avoid copy/paste of xsl file is to export a layer from ArcMap to KML. There is a simple tool ‘Layer to KML’ available at all license levels. When exporting you have to specify output map scale. This is required because if layer is not visible at export scale it will not be included in KML file. In addition symbology for the layer is driven by this scale.

Created KML works very nicely in AGX but this introduces data redundancy and makes maintenance a bit more difficult since two datasets have to be maintained.

Here are examples of KML file in AGX.

KML file added to AGX

Image source location from local hard disk

Image source location from the Internet and resized

This shows you how to take advantage of HTML popup and maybe encourages you to start using HTML popup. I'll review this again when ArcGIS 9.4 or next release of ArcGIS Explorer are released.