DroneDeploy and Reach RS?

Hello everyone.
I’m new to RTK/GCP, I have a few questions.

  1. Can I use the Reach RS to get GCP’s that i upload to DroneDeploy??

  2. Are the GCP locations measured in WGS84 (EPSG Code: 4326) ??

  3. Do I need 2 Reach RS’s to get 5-10 GCP’s??

  4. Will the GCP’s after processing by DroneDeploy give me centimetre accurate maps??

Thank you.

DroneDeploy and Reach RS?
That is the perfect marriage😊
I am sorry cos i also newbi to this tech, but from my walkarround on this great forum i can clearly see that your requirement is the simple job for reach. I suggest you to go much further on this forum…

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I am also thinking of using a rech and reach RS combination with my drone (mostly out of curiosity right now). As far as I see you may have several things to consider:

To 1: sure, you can use it. It is an precise GPS, but…

  • To have a good relative position you need to have two units. One is a fixed station that is just collecting the GPS signals and calculate errors due to atmospheric conditions and so on.
    In this case you will be having exact distances from this base station, but it may be still very much from the real coordinates. So there are issues when you want to use this data for general georeferencing, but it may help in the stitching process.

  • If you have the exact known position of your Base station, you can enter it in the settings and will have exact, real coordinates. This can be a ground reference point nearby. Here in my City we have a known coordinate points which is directly accessible, to check GPS receivers and so on. You would need to check that for each place you fly

  • There are already basestation networks which the reach could possibly use, but these are sometimes only accessible for a fee, you need to find the nearest basestaion and it has to be nearby (within 10km or so). So your place to work will be somewhat limited of you need to rely on an existing basestation network and one Reach Unit.

To 2: Emlid now just released a new Firmware with the ability to record Points (GCP’s) At this point in time it is only possible to save the points in WGS84… So yes, that will be no problem. You don’t need a separate program for that anymore.

To 3:. See me comments on point 1. For good absolute Positions you need 2 Reach/Reach RS and the known point of the base station. You can use an average over a longer period of time to set the coordinates of the Basestation but it is not as accurate as a known, properly set up reference point.
For relative coordinates two Reach RS is just fine.

To 4: Ok, that one is a bit more tricky… There are errors due to the GPS but also due to the stitching Process. Remember that the Software will search for similarities in the overlapping images, so there will be an error depending on the camera (lens distortion) as well as the calculation process as well… Never expect perfect results… However, you can try to minimize these errors (good cameras, good GCP’s, correcting lens distortion). Anyway, you will also see some errors in the stitching itself (warped roads, artifacts and so on). So if your image already is looking a bit distorted, you could probably not say it’s “centimetre accurate”. Please don’t just rely on advertised words. Try it out and check what is possible. Always keep an eye open and a bit of doubt in your results. There is a reason why they can still sell very expensive RTK GPS Systems and even more expensive photogrammetric packages. If it would be that easy for everybody…

That was solely my short experience with UAV’s, Stitching and GPS knowledge. I hope ti can help you a bit. You can use a free account on drone deploy to test it and I am sure you find some drone imagery for testing on the internet as well. Give it a try…


Does someone have a DroneDeploy GCP template file? Would appreciate if someone posts it here, we will consider adding it as export format for points on Reach.

Most processing and engineering programs accept a simple xyz text file. Generally, Point ID, X, Y, Z, Description, Status (Fixed, Float), error Rms X, Y Z. The status and error are additional field that can be added. If i may, offer an Export solution as too a data collection template., Export as Text, autocad, Coordinate conversions, and ability to identify the fields and order of fields in an export… possible a mailto: command for workflow ease. ect.

Thank you, but I was specifically interested in the DroneDeploy format, so that point can be exported there without any conversions.

You can. A quick understanding of Survey Grade GPS Results.
When set a base station up, you will be set up with arbitrary coordinates (Best guess 3-5 meter accuracy) You must record a static session (The base station records gps signals for a certain amount of time, depending of satellites seen, location, ect, for at least two hours). During this time you can record your GCPs with your rover (Your still on arbitrary coordinates).

After you record your data, you can post process your base station coordinate file. This will give you a precise X,Y,Z, to your base station. If you have recorded your GCP’s you will need to recalculate the coordinates by using the delta value between your original base coordinate and your processed coordinate. Translate your recorded points by those deltas and you have a complete accurate XYZ for your GCP’s.

Two receivers are best, for work flow, or you may complete static sessions on each point, or if you have a network to pull corrections from using your cell phone.

5-10 GCP’s for centimeter accuracy, depending on area plan on using more. You also want to include check targets for you can judge the accuracy of your map

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The following is part of a text file *.txt that can be uploaded. These are in state plane, wgs84, would be the same, with decimal degrees. Majority of programs accept this format.

1,1135572.3520,585649.2252,578.70,NAIL PARK LOT
2,1135452.8168,585820.2333,590.15,NAIL TOP BANK
3,1135319.0146,585864.2690,599.83,NAIL CEM
4,1135227.1216,585815.2339,591.80,NAIL CEM BY ROAD

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@skybumnd thank you, much appreciated!