Automatic Area Calulation whitout a map

Hi Survey Solutions Team

I would like to suggest a new feature in survey Solutions. It would be very interesting to have a feature similar the "geotrace” question type of ODK to be able to walk around a plot and get directly the area through the points that are captured automatically by the system. We are working in the field of Agricultural Statistics and we recently adopted Survey Solutions to conduct Survey in a nationwide scale but we are limited in having the area and the perimeter of agricultural plots of the households. It would be very difficult to upload the maps files of the entire country in the headquarters and then download them on tablets.
We hope to see this feature in the future releases of Survey Solutions.

Thank you

Hello @mougadjo ,

  1. Survey Solutions already allows you to capture multiple (x,y) locations when a GPS question is placed in a roster. What formula does ODK use to calculate the area from a sequence of these points?

  2. You wrote “conduct Survey in a nationwide scale but we are limited in having the area and the perimeter of agricultural plots of the households. It would be very difficult to upload the maps files of the entire country in the headquarters and then download them on tablets.”. Your interviewers can only walk around the plot that they are physically present on, and if they know where they will go to conduct interviews (the location of the household) it will be clear which digital map (much smaller than the size of the country) would be relevant for it. So the offline maps method is suitable for this task.

But what will you instruct the interviewers shall do if the household reports owning a plot 1000km away? Go there? Perhaps not. So in that case the offline map could have delivered a measurement, but walking around - not.

So as usual, the problem is not the computational deficiency, but a conceptual one.

What is the country? What is the survey?

I was told that ODK is an open-source software. Could you please look into the code and see how they do it? Or if this is too technical have their developers explain their source?

Suppose you encounter a household where a member reports owning a plot 1000 miles away. (say inherited from a distant relative). What will be the instructions for the interviewer to measure this plot? As far as I know in-person GPS measurements are limited to the current enumeration area (colleagues from FAO may step in to clarify how they recommend doing this), but you seem to insist that ALL PLOTS must be measured, which I don’t think is feasible. Even if your interviewers are willing to travel there, they can’t do this alone, they do have to follow the owner, who needs to show them the boundaries of the plot. And he/she (the owner) will not travel so far. (I’ve routinely joined interviewers in piloting surveys, so seen this first hand):

So, you can’t carry the digital map of the whole country, because that map is too big for a tablet. And you can’t carry a map of the individual parcel of the household you are going to, because you don’t know where you are going yet (the households are to be selected). But you do know to which EA you are going, and the size of the EA map should be manageable for a tablet. If you do have internet connectivity you can utilize online maps, and not store the map data on the tablet at all, but I wouldn’t count on this in the remote areas.

Hi,

Thank you for these detailed explanations.