The ArcPad Team Blog

Unofficial stuff from the team behind the World's leading mobile GIS platform

Wednesday, June 13, 2012

ArcPad Photo Layer

A picture says a thousand words and including photographs into your ArcPad Project is a great way to enrich your data. With built-in cameras becoming a standard feature for many mobile devices, taking photographs is easier than ever before. There are many ways to incorporate photographs into your ArcPad Project, such as standalone or feature-associated photographs, taken with built-in or external camera hardware, with or without a GPS.

Today's Blog will focus on Cameras and Photo Layers - next week we will be looking at associating photographs with features and some example workflows using photographs in ArcPad. 

External Cameras
ArcPad can use either the camera that is built-in to your mobile device or an external camera. If you are using an external camera, there are two different methods of bringing your photographs into your ArcPad Project. The first is for GPS enabled cameras which have GPS coordinates embedded in the EXIF header of the image. These photographs can be displayed directly on the ArcPad map as a Photo Layer. There is also software available which can insert GPS coordinates into the EXIF header of photographs taken on a camera that is NOT GPS enabled. This is typically done by matching the time and date of the photo with the time and date of positions captured by a streaming GPS, such as the ArcPad Tracklog. 

Camera Settings (ArcPad Options)
The Camera Tab on the ArcPad Options Dialog is where you set the following options:

Camera: Choose the camera to be used by ArcPad. The chosen camera and camera settings are used in the following places:
- The Camera Tools in the QuickCapture Toolbar
- The Camera Tool on the Picture Tab of the Feature Properties dialog box
Only cameras that are supported on the device are listed in the Camera drop-down list. By default, the ArcPad Camera is selected. 

Picture Quality: Use the slider to specify the picture quality for the photo (JPEG) image file. The range of the picture quality is from 50% to 100%. The default is 75%.

Default Pictures Path: Browse to specify the default folder for saving standalone photographs, i.e. photos that are taken using the stand-alone camera tool on the QuickCapture Toolbar. Photos taken using the Camera tool on the Pictures tab of the Feature Properties dialog box are automatically saved in the same folder as the associated shapefile or AXF. The default is \My Documents\My Pictures folder. 

NOTE: If you take a standalone photograph in ArcPad without a Photo Layer in your map, ArcPad will use the Default Folder Path to store photographs and the ArcPad.aph file created by default.

Filename Prefix: Enter the prefix to use for the file name of the photo captured with the Camera tool on the QuickCapture toolbar. The file names for photos captured with the Camera tool on the Picture tab of the Feature Properties dialog box use the selected field name for the prefix. The default prefix is 'Photo'. 

Button: Choose the button (on Windows Mobile and Windows CE devices) or function key (on PCs) to be used as a shortcut for starting the stand-alone Camera tool. This field includes a key-watcher to make it easier for you to find the name of your function keys/buttons by ‘watching’ to see which key/button you choose when the field is selected.

Date/Time in Filename: When checked, the file name for any photo taken consists of the date and time added to the prefix (for stand-alone photos) or field name (for photos associated with a feature), using the following conventions: Prefix_YYYYMMDD_HHMMSS.jpg FIELDNAME_YYYYMMDD_HHMMSS.jpg When unchecked, the file name for the photo is Prefix_nnnn.jpg or FIELDNAME_nnnn.jpg, where “nnnn” is a sequential unique number. 

Using an ArcPad Photo Layer
An ArcPad Photo Layer is a file that references photos with GPS coordinates in the EXIF header of each photo file. The Photo Layer file, which has an .aph extension, specifies how the photo layer should be displayed in ArcPad. ArcPad reads the GPS coordinates in the EXIF header, and automatically projects the latitude and longitude coordinates into the projection of the current ArcPad map.

A new Photo Layer can be created using the ‘New’ menu. ArcPad will also create an ArcPad.aph file in the nominated Pictures Folder by default if you begin to take standalone photographs in your project without a Photo Layer. 

The Identify and Hyperlink tools can be used with the Photo Layer. The Identify tool displays the photo’s attributes, or EXIF information, in the Feature Information dialog box. The Hyperlink tool displays the photo, using the external application associated with JPEG files.

Photo Layer Symbol and Label Settings
By default, a Photo Layer will be symbolised using a camera icon and labelled using the photo file name. The ArcPad Photo Layer is an XML file and can be edited in any text editor (eg. Notepad).

 <PHOTOLAYER title="Photos">
<FILEFILTER filter="*.jpg"/>
<TEXT visible="true"/>

To set the symbol, use <SYMBOL>  tags to describe any of the following symbol types:
See the Customising ArcPad Help for more information on symbol properties.

To label the symbol with the name of the photo file, use use <TEXT visible="true|false"/>.
NOTE: This method can also be used to control the visibility of the symbol .

For example, if I wanted to use a blue diamond symbol and label my photo points, I would modify my Photos.aph file in Notepad to read as follows:

 <PHOTOLAYER title="Photos">
<FILEFILTER filter="*.jpg"/>
<SYMBOL visible="true">
<SIMPLEMARKERSYMBOL angle="30" color="0,92,230" outline="255,0,0" outlinetype="solid" outlinewidth="0.75" type="diamond" width="8"/>
<TEXT visible="true"/>

Adding a Photograph to the Photo Layer in ArcPad
In ArcPad, the Photo Layer Camera Tools are located on the far left-hand side of the QuickCapture Toolbar. These Camera tools are used to take standalone photographs, that is, photos which are captured in a Photo Layer and not associated with a feature. You can choose to take a photo that has embedded GPS coordinates, or a photo that you manually place on your map using a pen touch.

To take a photograph that will include embedded GPS coordinates (from a connected GPS) tap the GPS Camera Tool on the QuickCapture Toolbar when the GPS is active.

To take a photograph that will be manually placed on the map, tap the Capture Photo Point Tool on the QuickCapture Toolbar. Then tap on the map at the location where the photo corresponds to.

In both of the cases described above, once the photograph is captured, the default Photo Layer will automatically (if not already present) be added to your map, and the photo location displayed.

When activated, each of the Camera Tools will open the same dialog box for interacting with your digital camera and for taking the photos. The Camera Dialog Box will vary according to the camera driver selected in ArcPad Options, but its properties may include camera orientation settings and photograph size and resolution.

Export Photo Layer to Shapefile
Be sure to check out this previous blog post to see how to export your Photo Layer to a Shapefile.

I hope this encourages you all to see the potential for including Photo Layers in your existing ArcPad projects and that you will consider using Photo Layers in any new projects.