Geoshape
Geoshape questions allow respondents to draw shapes on a map, capturing complex geographical data as part of the survey.
The geoshape question type in XLSForms and rtSurvey enables respondents to draw shapes (polygons) on a map, capturing complex geographical data. This feature is particularly useful for mapping areas, defining boundaries, or marking regions of interest in spatial surveys.
Basic XLSForm Specification
| type | name | label |
|---|---|---|
| geoshape | field_area | Draw the boundary of the field |
For more details on the basic geoshape question type, see the XLSForm specification.
Uses
Geoshape questions are commonly used for:
- Mapping field boundaries in agricultural surveys
- Defining areas of environmental impact
- Marking zones in urban planning studies
- Outlining regions for geological surveys
- Capturing complex geographical features for spatial analysis
Best Practices
- Ensure the device has location services enabled and permissions granted.
- Provide clear instructions on how to draw the shape and what area should be included.
- Consider using satellite imagery or base maps to help respondents accurately draw shapes.
- Be mindful of the potential complexity of shapes and their impact on data size and processing.
Example Usage
Here’s an example of how you might use a geoshape question in a survey:
| type | name | label | hint |
|---|---|---|---|
| geoshape | forest_area | Outline the boundary of the forest patch | Use at least 3 points to create a closed shape |
rtSurvey Extensions
While the basic XLSForm specification for geoshape 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 shape
- Ability to edit or refine shapes after initial drawing
- Support for different shape types (e.g., rectangles, circles) in addition to free-form polygons
(Note: The specific extensions available in rtSurvey for geoshape questions would need to be confirmed and detailed here.)
Data Format
Geoshape data is typically stored as a string of space-separated coordinate pairs, enclosed in parentheses:
(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; 38.253094215699576 21.756382658677467)
Considerations for Analysis
When using geoshape 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 shapes
- Privacy and data protection measures for handling detailed spatial data
- Integration with other spatial data sources for comprehensive analysis
Limitations
- Drawing accurate shapes on small mobile screens can be challenging.
- Complex shapes may require significant storage and processing capacity.
- Geoshape questions may not be suitable for all types of surveys or respondents.
- There may be privacy concerns associated with collecting detailed spatial data.