Using Trimble GeoExplorer to set up GCP’s?

AMann · Apr 21, 2020

Hello,

Has anyone used Trimble GeoXH’s (or similar) for establishing GCP’s (Post-processed)? I recently acquired a set of used handheld ones to use in the field (needed GPS data collectors that I could easily throw in an backpack to do backcountry fieldwork), and decided to get rid of my other RTTK units that are more suitable for mounting on tripods and poles for standard survey use. I am a mainly curious how accurate yours were and how you set them up when shooting GCP’s. Thanks!

Oh, if anyone is interested in my other units:

Sold! Emlid Reach RS+ Base and Rover UAV Aerial Ground Control Point Kit (like new open box) - $1500

Hello, I will be selling a complete UAV Aerial Photo Ground Control Kit on eBay (starting soon) and wanted to post it here at a lower price for members. My eBay user name is “eumops-calls” and I’ve sold and bought a lot of expensive items there and have 100% feedback. The kit includes 2 Emlid...

commercialdronepilots.com

R Martin · Apr 23, 2020

AMann said:
Hello,

Has anyone used Trimble GeoXH’s (or similar) for establishing GCP’s (Post-processed)? I recently acquired a set of used handheld ones to use in the field (needed GPS data collectors that I could easily throw in an backpack to do backcountry fieldwork), and decided to get rid of my other RTTK units that are more suitable for mounting on tripods and poles for standard survey use. I am a mainly curious how accurate yours were and how you set them up when shooting GCP’s. Thanks!

Oh, if anyone is interested in my other units:

Sold! Emlid Reach RS+ Base and Rover UAV Aerial Ground Control Point Kit (like new open box) - $1500

Hello, I will be selling a complete UAV Aerial Photo Ground Control Kit on eBay (starting soon) and wanted to post it here at a lower price for members. My eBay user name is “eumops-calls” and I’ve sold and bought a lot of expensive items there and have 100% feedback. The kit includes 2 Emlid...

commercialdronepilots.com

I use Trimble Geo7X mapping grade units on a tripod with a Zephyr antenna. We are connected via a data puck to an RTK net so we get real-time numbers in the field instead of having to post-process back in the shop. The accuracy via RTK Net is 2cm with my mapping package software installed. It's roughly the same (2-3cm) post-processing off one of TXDoT's COR sites that is about a mile away from me. You can boost that accuracy to survey grade for an additional ?$10,000.00 by installing the survey grade software package to your unit.

Back before AeroPoints, we had a set of 48X48" plywood panels painted white with a black cross on them. We drilled the center of each panel to set the tripod tip in the same place consistently. We converted to AeroPoints and are getting a lot better accuracy with them (survey grade). But a set of ten runs about $6200.00.

Dave Pitman · Apr 24, 2020

R Martin said:
But a set of ten runs about $6200.00.

Don't forget to factor that nasty subscription fee forever (currently min $600/yr) I know, insignificant for what surveyors charge but still, for non-surveyors it's spendy.

Also, I think the OP is operating in the field on foot out of a backpack.

AMann · Apr 24, 2020

R Martin said:
I use Trimble Geo7X mapping grade units on a tripod with a Zephyr antenna. We are connected via a data puck to an RTK net so we get real-time numbers in the field instead of having to post-process back in the shop. The accuracy via RTK Net is 2cm with my mapping package software installed. It's roughly the same (2-3cm) post-processing off one of TXDoT's COR sites that is about a mile away from me. You can boost that accuracy to survey grade for an additional ?$10,000.00 by installing the survey grade software package to your unit.

Back before AeroPoints, we had a set of 48X48" plywood panels painted white with a black cross on them. We drilled the center of each panel to set the tripod tip in the same place consistently. We converted to AeroPoints and are getting a lot better accuracy with them (survey grade). But a set of ten runs about $6200.00.

Dave Pitman said:
Don't forget to factor that nasty subscription fee forever (currently min $600/yr) I know, insignificant for what surveyors charge but still, for non-surveyors it's spendy.

Also, I think the OP is operating in the field on foot out of a backpack.

I’m also planning on using Trimble’7xs for wildlife studies for a different job, that’s a separate part from my question above- I was hoping to use them at school too, since my school also purchased Trimble7x’s for our technology classes (we got a surplus sale lot, and I was able to pick up a pair also).

So, when we start up again next year students will use them to learn about mapping by surveying the school grounds. It will integrate geography (GIS), math and physics into our curriculum. So, they got a set of older Geo7x’s along with some extra survey gear and a total station. They asked if I could teach that program with them hence my question above. Sounds like it will be a good matchup- 2-3 cm sounds pretty good! The students should also be able to quickly adapt to the Trimble menu and be able to work independently. I’m also happy about how rugged the units are!

R Martin · Apr 26, 2020

AMann said:
So, when we start up again next year students will use them to learn about mapping by surveying the school grounds. It will integrate geography (GIS), math and physics into our curriculum. So, they got a set of older Geo7x’s along with some extra survey gear and a total station. They asked if I could teach that program with them hence my question above. Sounds like it will be a good matchup- 2-3 cm sounds pretty good! The students should also be able to quickly adapt to the Trimble menu and be able to work independently. I’m also happy about how rugged the units are!

We give our students an intense exposure to mapping coupled with ArcGIS 10.6 and now Pro. The students we accept into the program graduate with real world experience that gives them a definite advantage compared to students that just go through the classroom/degree curriculum. We also get labor at a reduced rate.

AMann · Apr 27, 2020

R Martin said:
We give our students an intense exposure to mapping coupled with ArcGIS 10.6 and now Pro. The students we accept into the program graduate with real world experience that gives them a definite advantage compared to students that just go through the classroom/degree curriculum. We also get labor at a reduced rate.

Sounds great, what grade level are you teaching? For mine, it’s our middle school aeronautics club. Before I changed careers and starting teaching 5 years ago, I used to use ArcGIS at a former job doing environmental consulting (wildlife biology) and still occasionally do short contract work with it, and my wife is using it for her archaeology work. I also help her company out on occasion by doing aerial mapping for them.

R Martin · Apr 27, 2020

AMann said:
Sounds great, what grade level are you teaching? For mine, it’s our middle school aeronautics club. Before I changed careers and starting teaching 5 years ago, I used to use ArcGIS at a former job doing environmental consulting (wildlife biology) and still occasionally do short contract work with it, and my wife is using it for her archaeology work. I also help her company out on occasion by doing aerial mapping for them.

Undergrads. We accept them on a two year basis to help us do our jobs and in return we expose them to a grad level work environment. They perform day to day campus and utility mapping for us in addition to providing map services, project services and their own personal project that they choose. By the time they are applying for their first GIS job they have 2 years of production experience and at least one large project that they managed from start to completion.

adm_geomatics · Apr 27, 2020

AMann said:
Hello,

Has anyone used Trimble GeoXH’s (or similar) for establishing GCP’s (Post-processed)? I recently acquired a set of used handheld ones to use in the field (needed GPS data collectors that I could easily throw in an backpack to do backcountry fieldwork), and decided to get rid of my other RTTK units that are more suitable for mounting on tripods and poles for standard survey use. I am a mainly curious how accurate yours were and how you set them up when shooting GCP’s. Thanks!

Oh, if anyone is interested in my other units:

Sold! Emlid Reach RS+ Base and Rover UAV Aerial Ground Control Point Kit (like new open box) - $1500

Hello, I will be selling a complete UAV Aerial Photo Ground Control Kit on eBay (starting soon) and wanted to post it here at a lower price for members. My eBay user name is “eumops-calls” and I’ve sold and bought a lot of expensive items there and have 100% feedback. The kit includes 2 Emlid...

commercialdronepilots.com

It depends on your desire and definition of accuracy. The Geo7x as claimed is not a consistent 2cm accuracy unless you are on NTRIP and occupy the point for at least 30 minutes. Return stakeouts prove that and it is why it is marketed as a decimeter product. Back to the GeoXH if you are ok with sub-foot and at best 7-10cm then yes they are fine. Again you might get a little better if you occupy it for longer than the 7x, but that is not efficient. That accuracy will get you approximately +/- 3-5 inches on stakeout.

...both of the maximum accuracies stated are with an additional external antenna of which the Trimble Zephyr 2 or 3 is recommended and new are $1500+. In addition you need the NTRIP corrections which is usually a fee if you want consistent connectivity in a wide range of areas.

If you are doing this for construction then you are wasting your time.

AMann · Apr 29, 2020

chasco said:
It depends on your desire and definition of accuracy. The Geo7x as claimed is not a consistent 2cm accuracy unless you are on NTRIP and occupy the point for at least 30 minutes. Return stakeouts prove that and it is why it is marketed as a decimeter product. Back to the GeoXH if you are ok with sub-foot and at best 7-10cm then yes they are fine. Again you might get a little better if you occupy it for longer than the 7x, but that is not efficient. That accuracy will get you approximately +/- 3-5 inches on stakeout.

...both of the maximum accuracies stated are with an additional external antenna of which the Trimble Zephyr 2 or 3 is recommended and new are $1500+. In addition you need the NTRIP corrections which is usually a fee if you want consistent connectivity in a wide range of areas.

If you are doing this for construction then you are wasting your time.

Thanks for clarifying this- I am using it in an educational role at school, so we are using it as a learning tool for doing mapping projects on campus for demonstrations and labs. As for my other contract work, I do wildlife surveys and need to plot burrow and nest locations, and mapping vegetation for wetland delineations, so the accuracy is very good.

Your information above will also be valuable for those interested in doing construction and other mapping projects. Thanks!

AMann · Apr 29, 2020

R Martin said:
Undergrads. We accept them on a two year basis to help us do our jobs and in return we expose them to a grad level work environment. They perform day to day campus and utility mapping for us in addition to providing map services, project services and their own personal project that they choose. By the time they are applying for their first GIS job they have 2 years of production experience and at least one large project that they managed from start to completion.

Sounds like a great program, what school? PM me if you don't want to post it here, our HS graduates may be interested!

adm_geomatics · Apr 29, 2020

AMann said:
Thanks for clarifying this- I am using it in an educational role at school, so we are using it as a learning tool for doing mapping projects on campus for demonstrations and labs. As for my other contract work, I do wildlife surveys and need to plot burrow and nest locations, and mapping vegetation for wetland delineations, so the accuracy is very good.

Your information above will also be valuable for those interested in doing construction and other mapping projects. Thanks!

You may also test out using Google Earth for rough GCP's. This is a method we sometimes use to maintain relativity between sites when accurate grading is not needed. You basically use two plugins to acquire meter accurate coordinates and orthometric elevations to use in a GCP file to be used for processing. We use this primarily for GIS support projects, but also construction projects where we want to be able to track materials quantities and compare maps side-by-side for horizontal logistics and progress tracking. You can do the same thing a little more accurately with additional exhibition capabilities in QGIS or other GIS software.

Acquiring more accurate orthometric heights than the GE display.