Combining the Onboard GPS Capability of Smartphones with KML Files

July 15, 2015  - By
Image: GPS World

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By Jay Satalich, P.L.S.

At Caltrans District 7 in Los Angeles, we use the onboard GPS capability of smartphones to navigate in real time to the locations of proposed aerial targets and NGS control stations.

KML files are created in the office using desktop GIS, then downloaded to smartphones for use in the field. We create KML files specifically for use by our surveyors during every aerial mapping project within Los Angeles and Ventura Counties.
The aerial target layer also shows the proposed locations of stereo model limits on the smartphone.

Having the stereo model limits as a data layer becomes a handy piece of information in the event an aerial target needs to be relocated due to unfavorable field conditions. The heads-up capabilities of GPS aboard the smartphones and KML files can also show the easiest path to reach either target location or control stations. The NGS control station layer hyperlinks to the NGS website so the field surveyor always has the recovery note available in an electronic format.

The field surveyors are also given hardcopy maps of the target locations and control stations, but those are now only used as a back-up to the KML files loaded onto the smartphones.

We have found that leveraging the onboard GPS capability of smartphones with GIS-based data layers in the field has increased production. Using smartphones provides the surveyors with information more concisely and clearly, so better decisions can be made while in the field. The project surveyor has the ability to tailor datasets specifically to project needed by the field surveyors. 

Once the aerial targets have been placed and the NGS control stations recovered, the field surveyors then position the aerial targets and control stations using carrier phase GNSS.

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