Tuesday, December 23, 2008

How can I "stake out" points in ArcPad?

On many handhled GPS devices, you have the ability to "stake out" a point of interest. For example, you may know that you want to navigate to the nearest ice-cream store that has MGA94 coordinates of 527,105 5,251,855. How do you do this in ArcPad I hear you ask?

  1. Use the Find tool, and switch to the Location Tab.
  2. Make sure you change the coordinate system to what your coordinates are in (in this case MGA 94)
  3. Enter the coordinates of the location, specify the label on the map
  4. Click OK. The mark will be added to your map.
  5. Activate your GPS, open the GPS position window, and you will be given a bearing and a distance to travel in to reach your destination.

GPS Tracklog - Tips and Tricks

In recent times we have had a lot of queries about the GPS Tracklog in ArcPad - how it works, when it gets created, etc. etc. Here is a brief summary of things you should know.

How is it stored?
The GPS tracklog is stored as a point shapefile. Each point contains information such as the time, coordinates and quality estimates. ArcPad represents this shapefile as a line layer, which is what you see in the map when it is turned on.

Where is it stored?
By default, the GPS Tracklog is stored in My Documents. You can alter this from the GPS Tracklog Layer Properties, which can be accessed via the table of contents in the same way as any other layer.

When is the tracklog created?
The GPS tracklog is created when it is needed. If the shapefile is not present and the tracklog is turned on, it will automatically be created.

How do I start tracking?
Select Tracklog from the GPS drop down menu when your GPS is activated.

How do I clear the tracklog?
Stopped for a coffe and need to hide it from the boss? You can clear the Tracklog by clicking the Clear button from the Layer Properties of the Tracklog layer.

Can the tracklog log without showing in my map?
Yes. Open the Table of Contents, and you can toggle the visibility of the tracklog. Behind the scenes, ArcPad will keep logging positions.

What can I do with the tracklog at the end of the day?
As the tracklog is a shapefile, you can copy it off the device and store it back in the office. You could even create a Geodatabase, and store each day's log in there.

Tuesday, December 16, 2008

What is the RMS Error?

The Root Mean Square (RMS) Error is an important parameter which is frequently used in GIS. The RMSE is used as an indictor of the accuracy of the spatial analysis and/or remote sensing.

The RMSE is a measure of the differences between the predicted or calculated values and the actual, or observed/measured, value. Each individual difference between the calculated and actual value is called a residual. The RMSE aggregates the residuals into a single measure.

The RMSE is derived by squaring the differences between the actual and calculated values, adding these residuals together, dividing that by the total number of values, and taking the square root of the result.

Optimising PDA battery life

Optimising PDA battery life
Optimising the battery life of your Mobile Device increases the efficiency of your Mobile GIS System. Here is a list of some of the modifications you can make to your Mobile Device to let you make the most of your time out in the field.

Cycle through and set options for Battery Power, External Power, Brightness, Keypad Battery e.g. turn off backlight if not used for x minutes, set the screen brightness

Monitor and select power settings for your Mobile Device e.g. turn off device if not used for x minutes

Check battery calibration status, and re-calibrate battery if recommended (only available on selected devices)

Monitor the free/available memory on your device.

Start/Settings/Memory/Running Programs
Monitor running programs and stop programs that may be churning up memory e.g. ActiveSync, Email, etc

Monitor the integration of your Mobile Device with other devices through Bluetooth, Wireless Manager and other Connection options, e.g. maintain Bluetooth connection when device is turned off, turn on/off Bluetooth and Wireless connections.

Thursday, December 4, 2008

Transferring photos from Ricoh cameras via BT

So that no one else has to stoop as low as I did and have to read the user manual, here is how you set up the Ricoh / iPaq to give the option to transfer photos via BT immediately after it has been taken.

Make sure BT is switched on on the iPaq

Configure the iPaq to receive the images

  1. Open the Bluetooth settings (Start -> settings -> Connections -> Bluetooth)
  2. Switch to the Services tab
  3. Select File Transfer
  4. Turn off “Authorization Required” and “Authetication (Passkey) required”
  5. Hit Advanced, and specify the folder to store the images to

Enable QuickSend on the Ricoh

  1. Press the [Menu OK] button
  2. On page 3 of the EXP SET page, change the quick send method to “1TOUCH”

Establish a BT connection between the Ricoh and the iPaq

  1. Press the [Menu OK] button
  2. Go to page 2 of the EXP SET page
  3. Select BT SERIAL, then click Right
  4. Click [ADJ] to search for devices in range
  5. Select your iPaq and press [MENU OK]
  6. Exit out of the menu – you should see the BT icon on the display

Send a photo to the iPaq

  1. Take a photo
  2. Hit the PLAY button
  3. Press [MENU OK] button, and switch to the 2nd page of the PLBK STGS menu
  4. Click RIGHT on the FILE SEND option
  5. Select your device
  6. Click SEND ONE

You will see a dialog on your iPAq confirming that you want to accept the image From now on you get the option to send the image when the quick review is displayed after an image is taken

  1. Click [OK MENU] during the quick review to send the image
  2. You will need to confirm the transfer from the iPaq also

Note that you can get the ricoh to establish the BT connection when it starts up by selecting [BT AUTO CONN] on the 2nd page of the EXP SET menu.

Monday, December 1, 2008

Bluetooth GPS Vs CompactFlash GPS - Which one suits me?

A common question for Mobile GIS users is whether to purchase a Compact Flash (CF) or Bluetooth (BT) GPS. Basically there is no wrong choice as both GPS receivers are functional devices in their own right and will provide a useful addition to your Mobile GIS system. The majority of BT and CF GPS receivers on the market these days come with chipsets that give them a standard positional accuracy of ±2-5 metres. Here are some points to think about when choosing between a BT and CF GPS receiver:

Compact Flash GPS
- Fits into the CF Slot of your PDA/UMPC/Laptop to make an ‘all-inclusive’ unit
- Limited to integrating with devices with a Compact Flash slot
- The battery of your Mobile Device is used to power the CF GPS, resulting in the battery life of your PDA/UMPC/Laptop dropping by up to half its standard lifespan

Bluetooth GPS
- Has its own battery independent of your PDA/UMPC/Laptop, so the battery life of your mobile device is not compromised
- Adaptable nature of Bluetooth allows integration with an increasing number of devices (e.g. PDA, Camera, Mobile Phone, etc )
- May be another piece of equipment to worry about in the field in addition to your mobile device (albeit a very small piece)