Illinois Historical Aerial Photograph Interactive Map Launch Page

Digital versions of ILHAP photographic paper prints are available by county as MrSID compressed <filename>.sid files, which can be saved to your computer's hard drive. Alternatively, the .sid files may be viewed either with your Web browser, after the installation of a plug-in.

Instructions for downloading Illinois Historical Aerial Photography in MrSID format, a screen shot of the Interactive Mapping Web Interface, and descriptions of the navigational tools of the Interactive Mapping Web Interface are detailed below.

Instructions for Downloading Illinois Historical Aerial Photography in MrSID Format

Environmental Settings for Interactive Mapping: Your browser must have Frames and JavaScript enabled.; The Web interface is best viewed using Internet Explorer.; It is not possible to bookmark map views. Instead, bookmark this access page.

Helpful Hints: Map manipulation tools are offered on the left side of the interface.; Data layer visibility and activation control are offered on the right side of the interface.; The icon outlined in red is the current tool. (i.e. the icon for the "Zoom In" tool is outlined in red in the screen shot shown below); To select a tool, click on the desired icon.; Choose an appropriate viewer window size. Resizing the viewer window after zooming in will cause the interactive map to reload and display the statewide map view.

Step 1: Enlarge an appropriate area.: Use the "Zoom In" tool (default) by clicking or drawing a box around an area of interest.

Step 2: Create a custom map view.: Select a combination of data layers by toggling the "Visible" layers ON or OFF.

Step 3: Click the "Refresh Map" button.: The "Refresh Map" button is listed below all data layers and will update the newly selected "Visible" layers. Data layers "Interstates", "Counties", and "1938-1941 Photo Centers" are set to "Visible" in the screen shot shown below.

Step 4: View a photograph.: Use the "View One Photo" tool to select a photo to be viewed in the MrSID plug-in or viewer.

Step 5: Choose the "Active" layer.: Designating a layer as "active" allows features within that layer to be selected. Only one layer can be designated as "active". In order to successfully follow the next step, the "Active" layer should be set to "1938-1941 Photo Centers". The "Active" layer can be changed without clicking the "Refresh Map" button.

Step 6: Access detailed photograph data and download photographs.

Use the "Select Multiple" tool to select multiple photographs or one photograph. In the lower frame, detailed data about each selected photograph will be displayed in table format. Find the hyperlink in the last column of data.

To view a photograph, click once on the hyperlink. The photograph should appear in the MrSID plug-in or viewer.
To download a photograph, right-click on the hyperlink. Choose "Save Target As..." from the list of options. Browse to a file storage location and save the MrSID format file.

Representative screen shot of Interactive Mapping Web Interface

Navigational Tools of the ILHAP Interactive Mapping Web Interface

	Overview Map	Turn the Overview Map displayed in the upper left corner of the map frame on or off.
	Zoom In	Enlarge the map image by clicking on a spot or dragging a rectangle around the area of interest.
	Zoom Out	Reduce the map image by clicking on a spot or dragging a rectangle around the area of interest.
	View One Photo	Graphically select a single photograph for viewing. A separate file-viewing window appears to display the photograph if you have downloaded the appropriate MrSID plug-in or viewer. There is no need to specify an "active" layer.
	Select Multiple Records	Graphically select multiple records by dragging a rectangle around the area of interest. Features in the rectangle will be selected and highlighted in light blue. A table of information pertaining to the active layer will appear. For the "1938-1941 Photo Centers" layer, attributes for selected photographs include a link for viewing or downloading each file. The user MUST specify the "active" layer to the "1938-1941 Photo Centers" layer.
	Clear Data Selection	Unselect all selected features.
	Pan Map View	Drag the map image so that the area of interest is shifted within the view.
	Previous Extent	Return the map view to the previous zoom level and location.
	Zoom to Active Layer	Enlarge or reduce the map image to the fullest extent of the data layer selected to be the "active" layer.
	Zoom to Full Extent	Zoom the map view out to the the fullest extent of all data layers, in this case, the boundary of the state of Illinois.
	Print Map View	The user is prompted to submit a map title. After typing and submitting the title, a new window opens that contains a formatted title, map image, and legend suitable for printing. Use the browser "Print" button to print the map.
	Legend or Layers	Toggle between the layer list and the map legend. The layer list enables the user to set the active data layer and also set the display of individual data layers to be on or off. The legend is a graphical representation of the symbology of all visible map layers.