Geotrace
Geotrace questions allow respondents to capture a series of connected points on a map, creating lines or paths as part of the survey.
The geotrace question type in XLSForms and rtSurvey enables respondents to capture a series of connected points on a map, creating lines or paths. This feature is particularly useful for mapping routes, boundaries, or linear features in spatial surveys.
Basic XLSForm Specification
| type | name | label |
|---|---|---|
| geotrace | river_path | Trace the path of the river |
For more details on the basic geotrace question type, see the XLSForm specification.
Uses
Geotrace questions are commonly used for:
- Mapping routes or paths taken during field surveys
- Tracing linear features like roads, rivers, or boundaries
- Capturing the extent of linear infrastructure (e.g., pipelines, power lines)
- Recording travel paths in transportation studies
- Defining transects in ecological surveys
Best Practices
- Ensure the device has location services enabled and permissions granted.
- Provide clear instructions on how to trace the path and what features should be included.
- Consider using satellite imagery or base maps to help respondents accurately trace paths.
- Be mindful of the potential complexity of traces and their impact on data size and processing.
Example Usage
Here’s an example of how you might use a geotrace question in a survey:
| type | name | label | hint |
|---|---|---|---|
| geotrace | hiking_trail | Trace the path of the hiking trail | Start at the trailhead and end at the summit |
rtSurvey Extensions
While the basic XLSForm specification for geotrace questions is straightforward, rtSurvey may offer additional features or customizations:
- Integration with offline maps for remote areas
- Options to set minimum and maximum number of points for the trace
- Ability to edit or refine traces after initial drawing
- Support for automatic tracing at set intervals during movement
(Note: The specific extensions available in rtSurvey for geotrace questions would need to be confirmed and detailed here.)
Data Format
Geotrace data is typically stored as a string of space-separated coordinate pairs, similar to geoshape but without the closing point:
lat1 lon1; lat2 lon2; lat3 lon3; ... latN lonN
For example:
38.253094215699576 21.756382658677467; 38.25021274773806 21.756382658677467; 38.25007793942195 21.763892843919166; 38.25290886154963 21.763935759263404
Considerations for Analysis
When using geotrace questions, consider:
- How the geographic data will be visualized and analyzed (e.g., GIS software)
- The potential need for data cleaning or simplification of complex traces
- Privacy and data protection measures for handling detailed spatial data
- Integration with other spatial data sources for comprehensive analysis
Limitations
- Tracing accurate paths on small mobile screens can be challenging.
- Complex traces may require significant storage and processing capacity.
- Continuous GPS usage for automatic tracing can quickly drain device batteries.
- There may be privacy concerns associated with collecting detailed path data.