Project boundary shifts when I turn on my Arrow 100 GNSS

“I am having an issue with my Wetland Stakeout App that I believe I ran into in the past and figured out but this time I am unable to figure it out. I set up a project and imported a shapefile of a project area boundary in WGS 1984. Before leaving the desk/office I can see the project area boundary is accurate on the air photograph. When in the field and I turn the APP on everything looks correct but as soon as I turn my Arrow 100 GNSS Receiver on the project area boundary shifts about 30-40 feet to the south and my position is shown offset by the same distance.”

A shift of that magnitude is likely due to using the wrong coordinate system or distance unit.

It appears you have selected the correct datum, coordinate system and distance unit for importing the Shapefiles.

The SBAS data sent out by the Arrow 100 uses ITRF08 datum and meters distance unit. Please switch to Meters for distance unit in the Wetland & Stakeout app before turning the Arrow 100 on.



App for verifying survey drawing and recording building corners

“I have a survey drawing of my property and my property has metal stakes at the corner. I would like to verify the survey drawing to the stakes. I also would like to identify where the corners of my home is located on my property. What would be the best software for these requirements?”

Our Deed Calls function will let you enter bearing and distance information from your survey drawing to generate a plot in the app. You will need to know the coordinates of the point of beginning in order to correctly place the plot on the map.

Our Stakeout functions will help you get to a point or node (where the stake is supposed to be).

These functions are provided in a few of our apps, such as Deed Calls & Stakeout, iCMTGIS III and iCMTGIS PRO.

iCMTGIS III and iCMTGIS PRO also provide GPS data collection functionality that will let you record the corners of your home or any other points, lines and areas.

The important issue is what compatible GPS receiver to use to meet the degree of accuracy that you need. The GPS on iOS devices are good to about 10 meters.

GIS-grade GPS like the Bad Elf GPS and the Dual XGPS-150A claim 2 – 5 meter accuracy. You could use a GIS-grade GPS and Deed Calls & Stakeout to roughly check the stake locations against the drawing.

Survey-grade GPS devices from EOS and Geneq are quite expensive. You might be able to rent an iSXBlue Platinum or an EOS Arrow from a supplier to use with iCMTGIS PRO for best accuracy in stakeout and recording GPS points.

Where can I rent high-precision GPS receivers?

We are aware of a couple places that rent EOS Arrow and SXBlue Platinum GNSS receivers.

App for fencing property

“I am trying to find a app that I can use to find property corners and go from one corner to another in a straight line ( for fencing ) I have good surveys and legal descriptions to enter for my property. I would like to use my IPhone for this.”

With the legal descriptions and the coordinates of the point of beginning, you could create a deed plot in the Deed Calls & Stakeout app then use the Line Stakeout function to help you walk along the boundary line to find the property corners.

Now, the iPhone GPS is accurate to about 30 ft. An external GIS-grade Bluetooth GPS, such as the Dual XGPS-150A or a Bad Elf GPS, usually claims 2 – 5 meters accuracy (about 6 to 15 ft). You will need better accuracy for fencing a property boundary. You could use iCMTGIS PRO in conjunction with a high-precision GNSS receiver (such as a SXBlue Platinum or an EOS Arrow). The high-end GNSS receivers are very expensive. There are places that rent them out. You might check with them to see if the total cost justifies the one-time use.

App for stakeout and data collection

“I have researched a number of your available apps, and would like your input on which would be most useful for basic point/line/polygon stakeout and data collecting…..I usually receive staking requests from our engineers with PLSS information and footage calls. Often there is an attached KMZ from which I can grab geodetic information. Are any of your apps capable of working with NAD83 State Plane coordinates? And which one would be best for importing data into a job?”

Based on what you write, we understand that you would like to be able to

1) work with NAD83 State Plane coordinates

2) use GPS to record point, line and area features and collect data for the features

3) stake out point/line/polygon using GPS

4) enter coordinates for the point of beginning and enter deed calls

5) import data into a job

6) do survey quality work.

The combination of the iCMTGIS PRO app for iPad and iPhone devices and either the SXBlue Platinum or the EOS Arrow Gold high-precision GPS receiver is what other users are using for this type of work. Our app provides the functionality that you are looking for, but it is the GPS receiver that determines the accuracy of your work.

iCMTGIS PRO will let you import data as Shapefiles, Excel file, DXF and KML. It will also let you import Point data into a Topic layer via a text file.

App to help plant trees?

“I am wondering if any of your programs could be used in my tractor as a way to guide me in driving a straight line when planting Christmas trees? Even if it doesn’t help me row by row could it be used to help me lay out a planting? Help to drive the first line across a field?”

The GPS system you will need to guide a tractor along a line to plant Christmas trees requires a high-precision GPS receiver used in conjunction with an app that will let you record a few reference points, draw the line on the map and guide the tractor along the line.

The actual equipment and app you select will depend on the accuracy you wish to achieve. Of course, a high-accuracy system comes with a high cost.

The SXBlue Platinum and EOS Arrow Gold GPS receivers can be used with iCMTGIS III to achieve sub-meter accuracy.

The SXBlue Platinum and EOS Arrow Gold GPS receivers can be used with iCMTGIS PRO and a RTK network to achieve cm-level accuracy.

As there will also be visual cues to guide the tractor, do you think sub-meter accuracy will be sufficient for you?

Both iCMTGIS III and iCMTGIS PRO will let you load a geo-referenced background map (*.tif. *.pim or *.bmp). These are useful as a general reference, but they are not accurate enough to let you pin-point your first point or line by digitization.

You could use iCMTGIS III with a SXBlue Platinum or an EOS Arrow Gold GPS receiver to record the property boundary and the starting point to sub-meter accuracy. iCMTGIS III and iCMTGIS PRO will let you create a grid over the property to indicate where the trees are to be planted.

iCMTGIS III and iCMTGIS PRO provide the Stakeout functions to guide you along the grid lines. These apps will display how far the tractor deviates from the line. You could also set up the apps to keep beeping as long as the tractor stays on the line within the specified tolerance.

Which EOS GPS receiver to get?

Please refer to the comparison chart at the following link: