Continuously recording GPS coordinates based on user location (without pressing on the map for each dot)

  1. The combination of a Geography question and a Polygon geometry type allows a user to record areas, such as agricultural plots, but it requires the user to manually chose the vertices of the plot according to the online guidance for geography questions. To be explicit:

" Geography Question

Select an Area

The enumerator must select an area by pressing on the map for each dot that represents the coordinates of the area to appear. You can edit the shape by adding more coordinates or moving the existing dots/area. Once complete tap on Save."

** 2) Because of various issues, we would prefer if our enumerators could simply walk around an entire agricultural plot and have survey solutions continuously record the GPS coordinates around the perimeter based on their location, without requiring any manual identification of vertices/pressing of tablet screens.**

As far as I can tell, that combination of options is not available. But I may have missed an important detail of how to facilitate this? Or you may know of a practical workaround. Any ideas on how to proceed would be greatly appreciated.

Thanks in advance,
Esteban

cc: @zurab @sergiy

What survey is this? What are you measuring? With which instruments? What are the “various issues”?

Thanks for the quick response, Sergiy!

This is a survey in rural Niger that is part of an evaluation of an intervention that involves irrigation, road rehabilitation and access to market.

The core issues that I have in mind are that i) agricultural plots are irregularly shaped and sized + ii) pressing tablet screens tends to result in points at imprecise geo-locations, as opposed to exactly at the location(s) where the enumerator is standing/walking.

As such, it would be preferable for our field team to collect a continuous sequence of GPS points following the path the enumerator walks on the edge/boundary of a plot. This will enable our GIS analyst to generate the polygons that correspond to the plot after the fact, which we will use for various analytical tasks.

Any suggestions on how to proceed would be greatly appreciated!

In agricultural surveys I have been involved in such polygons were usually recorded using Garmin handhelds which
a) have the functionality you are looking for
b) have better GPS accuracy than consumer tablets

The interview can show a unique code (preloaded or generated from other variables like household id) which is then entered as the name of the coordinate file on the Garmin.

So you are measuring area of irregular agricultural plots. Assume for the moment they are rectangular. For a typical plot, what would be the error you are making in estimation of the area of that plot, if you measure the position at each corner with the tablet’s sensor accuracy? (check the settings of your App for the exact value). You will not like the result.

Klaus suggested an external GPS device. I’ve seen them being used in practice, but in the opposite direction, not storing the data in the handheld GPS device, but rather transferring back the calculated area. With obvious consequences that you are loosing the values of the coordinates.

Still has plenty of opportunities for mistakes, including misreading the indication of the device, mistyping (leaving a digit behind or double tapping), misplacing the comma, etc. But these are as with any other numeric question.

You can do it in the way Klaus suggested, but that’s an extra item to synchronize, and you will get lost pretty quickly, once your interviewers realize that the second plot is not eligible for this HH because it is rented not owned, but all the coordinates data has already been shipped to the office. (or a million of similar scenarios).

Instead you can look into external GPS sensors that are connecting to the Tablet by Bluetooth or WiFi and provide sub-meter precision of measurement. They add to the cost, training time, and make the ultimate solution more vulnerable. But the advantage is that the data transfer is automatic.

The offline maps arose as a solution for precise pointing, since with it YOU control the precision, and with better maps can get a better precision. With GPS you are limited by the technology, weather conditions, etc and can’t improve beyond that.

In the end it’s your call. If you go with the points approach, you may find this relevant:

Thanks @klaus and @sergiy !

We are using external GPS sensors for more accurate readings, but we have MANY fewer of those so they will primarily be used by supervisors.

The vast majority of our plot measures will have to come through the tablets one way or the other. We would prefer for that to take place in an integrated fashion with Survey Solutions if that is possible. Otherwise, we will likely have to pivot to Parcel Mapper.

One thing to note is that we are not only interested in the area itself, but also the GPS points/polygons because some of our analysis is explicitly spatial and we will be developing crop type maps, etc., in the project affected areas.

Again, thanks for your help and the suggestions/resources you have provided. Any additional suggestions on how to accomplish this work, especially if directly through Survey Solutions, will be most appreciated.

Kind regards,
Esteban

Hello Esteban, you didn’t say anything about Parcel Mapper. Is that some sort of software? Or website? Or a dedicated person who measures parcels?

If this is a software, please provide a link to the site/manual/download. Also, how would it solve the issue if the low accuracy is a hardware issue?? If the scale is inaccurate, it doesn’t matter which color you paint it.

Regards, Sergiy