Collect GPS locations by angle and distance offsets from observer location?

931
7
06-09-2022 09:41 AM
DavidMedeiros
Occasional Contributor III

I'm helping a field researcher get set up for a summer trip to a SA rainforest, collecting frog observations. She will be using Field Maps for this work (past studies used ArcPad). Because the observations will typically not be at the exact location of the observer, the usual method is to collect an offset (angle and distance do the observation from the observers taken GPS point). I guess ArcPad as an option to add this offset info during the point capture.

Is there a method for doing the same thing in Field Maps?

I see that Field Maps as offset capture instructions (here) but this seems to require a laser range finder which the group does not have funds for.

Edited to add: the offsets will be in degrees and meters (not centimeters). The distances are due mostly to having to take observations from outside sensitive or inaccessible habitat. Using the map pan method may not be accurate enough for them due to lack of hi detail base map information, but they do know how to accurately gauge the angles and distances. 

7 Replies
RobertBorchert
Frequent Contributor III

Well you should have no trouble getting a GPS signal in (I will assume) South America.

However, I doubt the researcher will get anything resembling a data signal on a phone or tablet, depending on how far from civilization.  

When you are talking off set, how much are you talking about?  I would think that for frog observations that centimeter accuracy is not needed. 

You should find out specifically what they need to collect.  

For the most part, if they have a device, they know their area of interest (geographically) you could set up off line maps and air photos and they could use the cursor on their phone to ball park the location pretty good. Well canopy cover would hinder that. 

Frontier Precision is a company local to me that provides excellent GPS solutions for a wide variety of needs. 

https://frontierprecision.com/

If the researcher does need to be super accurate you are probably going to go above their budget. 

 

0 Kudos
DavidMedeiros
Occasional Contributor III

See the edited post above for a little more detail. Basically they set down a single averaged hi resolution GPS point, then enter all their observations off that point by angle and distance in meters. They do not need centimeter accuracy. Apparently ArcPad can do this directly? But it seems Field Maps can not.

Yes, they will have GPS signal but no network. That's standard, they will download their maps for use offline and sync back to AGO later.

0 Kudos
by Anonymous User
Not applicable

I couldn't find a software solution in the docs either. Following this also incase I missed something. 

They might have to store degrees magnetic and meters as attributes... but in this day and age there should be a way to compute that on the device.

RobertBorchert
Frequent Contributor III

I would think for the best and most economical solution you would want to work closely with a Trimble or Garmin Provider.  Granted there are other GPS manufacturers but Trimble is very good, in my opinion.  My company currently exclusively uses Trimble.

 

Providing the offline maps should be pretty straight forward. 

0 Kudos
RobertBorchert
Frequent Contributor III

I would like to add that I would be interested to hear more about the project and how it come out. This sounds very interesting. 

0 Kudos
MaxRingler1
New Contributor III

Hello David,

likely you were talking about someone in Lauren O'Connells group, working with poison frogs or cane toads. In fact, their mapping technique is based on our paper and a workflow I developed 18 years ago

(Ringler, Max; Mangione, Rosanna; Pašukonis, Andrius; Rainer, Gerhard; Gyimesi, Kristin; Felling-Wagner, Julia et al. (2016): High-resolution forest mapping for behavioural studies in the Nature Reserve ‘Les Nouragues’, French Guiana. In: J Maps 12 (1), S. 26–32. DOI: 10.1080/17445647.2014.972995.).

Unfortunately, up to date I am not aware of a workflow in any current mobile software from ESRI that replaces the offsetting function ArcPad has. For that very reason we are still using the last, terribly outdated, version of ArcPad on rugged Windows tablets/handhelds to be able to work like we always did under dense rainforest canopy where GPS is simply not an option for decimeter accuracy.

I'd be highly interested, if you came up with a solution other than keeping on using ArcPad!

Kind Regards

Max Ringler
University of Bern

 

DavidMedeiros
Occasional Contributor III

Thanks Max. I think you are correct. I'll have to go back and look at the current version of Field Maps to see if this has been addressed, but it's unlikely. Esri moves at a glacial pace with these kinds of feature updates.

0 Kudos