Shapefiles do not match points recorded using GPS

“I have a site where I collected points plus 5 existing property irons of 7 known iron pins using iCMT Pro and an Arrow 100. I added the parcel shapefile to the project in PCGIS X. The available shapefile just does not match any of the irons. If I could find the deed or even better an old survey, what would be the best way or procedure to add that to the project in PCGIS X instead of the shapefile?”

If the Shapefiles and your GPS position for the irons don’t match, most likely it is due to the fact that the Shapefiles were prepared using a different coordinate system than the iron points. Please find out what datum/coordinate system and distance unit are used by the Shapefiles. Open the Job file containing the iron points, set the coordinate system to match that for the Shapefiles then import the Shapefiles.

If you can find the deed, you could use the Create Deed Calls function in PC-GIS X or in iCMTGIS PRO to generate the deed plot then use the Line Stakeout function on iCMTGIS PRO to help you find the other two pins. You will need to know the LAT/LON coordinates of the point of beginning. If the deed is based on magnetic north, then you will need to enter the local magnetic declination into the Orientation field for the Create Deed Calls function.

As you will be using Line Stakeout on the device running iCMTGIS PRO, you might as well enter the deed calls in iCMTGIS PRO as well. When the work is complete, you can transfer all data to PC-GIS X.

How to show contour lines as background image in iCMTGIS PRO

“… I have loaded a shapefile of parcels for a county. I have also loaded the contours of the county. With Edit > Copy, I have been able to select and isolate a specific parcel. How would I do that for the contours just on or around the selected parcel? I would like to clip the contours to show with the parcel whereas Edit > Copy selects the entire contour file. Right now I am getting the parcel only plus entire county contours. As you can imagine the .pmp file size is huge over 280000 KB while the parcel only .pmp is 14 KB.”

Yes, Shapefiles containing contour lines can be huge in file size. As each imported contour line counts as a Feature in our apps, the app will be slowed down a great deal or may even crash while trying to process all these Features.

If the contour lines are just for background reference in iCMTGIS PRO, you can use PC-GIS X to turn the map with the contour lines into an image then crop the part that you need.

For the following steps, please use the same datum/coordinate system as your Shapefiles.

1. Create a new job in PC-GIS X and load the Shapefiles for the contour lines. You can save this job for future use.

2. Use Utilities – Geo-image – Save to Registered Image to save the map image to a .tif file.

3. Create another new job and use the “L” (Load Registered Photo/Image) tool icon to load the .tif file that you’ve created.

4. Copy the desired parcel (Area Feature) from your main job to this new job that contains the contour map image.

5. In the new job, select Utilities – Geo-image – Crop and Save Image.

Click on the contour map image to select it as the Source Image then click on Next.

In the next window, choose “Select an Area Feature“.

Click on the parcel boundary then click Next.

You will be prompted to save the cropped image as a .pim file.

6. Now you can open your main job and use the “L” button to load the .pim file that you have saved. The contour map will serve as a background image in this job.

To use the .pim image in iCMTGIS PRO, you will need to copy it to iCMTGIS PRO then load it as the Background Image.

Very slow to load Features from Shapefiles

A customer reported that it took a long time to load Shapefiles containing county property lines.

The U.S. county property line Shapefiles typically contain more than ten thousand polygons, along with a multitude of Attributes. As we mentioned in our 10/2/19 blog post, it will take time for the app to process a large job with a huge number of Features and Attributes. The app might also crash if a computation or file saving operation is disrupted for some reason.

Typically, you will want to just load the polygons that you need for a particular job, and not all of them. If you have a PC software program that will let you load the county property lines then let you export just the ones that you need, then please use it to prepare the corresponding Shapefiles for importing into the app.

Some of the iCMTGIS PRO customers use our PC-GIS X to accomplish this. PC-GIS X can import and export Shapefiles. So, the users would load the Shapefiles from the county then select the polygons they need to export to a new set of Shapefiles for importing into iCMTGIS PRO. After collecting GPS data, they would copy the .pmp file to their PC and open it in PC-GIS X. Then they will see the Feature data displayed along with the property lines . They will be able to make some changes, if they wish, then use the Plot Preview function to make a nice map for printing to a PDF file or a printer.

If you don’t need to refer to the property lines in the field, then you could simply load the county property polygons into PC-GIS X and combine them with the field data to complete the map.

Where would I get a built-in background map that has at minimum local tax property lines?

Many states in the USA provide tax lot polygon maps on their website in the form of Shapefiles.

After you have downloaded the .zip file for the Shapefiles for your county, move it to your PC and unzip it to a folder on your PC. Use iTunes to copy the Shapefiles to the Documents folder of your iCMTGIS PRO, iCMTGIS III, iCMTGIS II, iGPSGIS II or Utility Data Collection app.

Then, you should be able to import the Shapefiles into a Job in your app. The data in the Shapefiles will become Feature Topics and Features in the Job, and you will be able to use them as background reference for doing GPS data collection.

What size Shapefiles can be loaded into iCMTGIS PRO?

From our experience, with 1 GB system RAM, Shapefiles about 350 MB in size is the largest that will load into the app.

It would be best to break up a very large job into smaller jobs. Large jobs with a huge number of Features (such as loads of points or contour lines) will take a while to process. If the computation or the file saving operation is disrupted for some reason, the app will likely crash.

Importing Shapefiles into Stakeout iCMT

“I just installed Stakeout on an IPad; I am not really an IPad user. I would like to import a shapefile from my PC; however, Stakeout only appears to know about its own Documents folder and I can’t find the Documents folder anywhere on the IPad. The instructions are to ‘sync using the ITunes app’ but I don’t see an ITunes app, only the ITunes Store app. Can you provide any guidance on how to do this?”

iTunes is a free software program provided by Apple.

The procedure for importing Shapefiles is described at this link:

The Stakeout iCMT app only displays coordinates in terms of latitudes and longitudes.

Which coordinate system to select when importing Shapefiles into iCMTGIS PRO?

When loading geographic position data into a mapping software program, the program needs to know which coordinate system the position data refers to.

When you import such position data into iCMTGIS PRO, it will display a window for you to specify the datum, coordinate system and distance unit so that it can place the geographic Features (shapes) in the correct map location.

Often the set of Shapefiles that you get comes with a .prj (projection) file. If you include this file with the files you copy to the Documents folder for iCMTGIS PRO, then when you import the Shapefiles, the app will display the proper coordinate system information, and all you need to do is to confirm it. You might want to write down this information if you don’t already know it.

Suppose you knew the reference coordinate system beforehand, and you have set the coordinate system in iCMTGIS PRO to match it before importing the Shapefiles, then the imported data will be displayed using that coordinate system.

On the other hand, if the working coordinate system is different from that used by the Shapefiles, then after the Shapefiles have been imported, the data will be displayed using the working coordinate system.

In other words, when you specify the coordinate system during the import process, it is strictly for use in interpreting the imported data. It does not change the currently active coordinate system.

Therefore, if you did not know the coordinate system information of the Shapefiles, you should write down the information displayed by iCMTGIS PRO during the import process, so that you could switch to that system later, if you wish.

Shapefiles for Chile shows up in North America

“We update de FORESTER GPS GIS II, on iPad from version 1.0.1 to 1.0.2 and we are having issues with the coordinate system when importing a shape file.The shape appears in North América and we are from Chile. We use UTM with Datum WGS84. Is there any suggestion on what can we do. I try this in two different devices with the new version and both have the same problem. When using it in the 1.0.1 version all goes OK.”

Please make sure you have selected the correct UTM Zone.

Please also copy the .prj file for the Shapefiles to the documents folder for Forester GPSGIS II.

What coordinate system do the Shapefiles use? If they are based on WGS 84 LLA, then try setting the Forester GPSGIS II to that coordinate system before importing the Shapefiles. After importing the Shapefiles, then change the coordinate system to UTM WGS84.

Use iPhone app to update attributes in Shapefiles

“I’m just wondering if I could use my I-phone for my surveying? Would iGPSGIS II allow me to import a table in shapefile format, update alphanumeric attributes in the field and then export it back to my PC? From the descriptions of this software it looks like i can only view ()not edit) the attributes of imported files.”

Yes, iGPSGIS II will let you import points/lines/areas with attributes as Shapefiles, update the attributes then export them in Shapefiles.

iCMTGIS PRO for electric pole staking

“So what I’m needing is software that can collect a start and end point for a new line and then take those and tell me where along that line to set my electric poles in order to keep them nice and straight in line with the starting and ending pole. Also it would need to be able to route me say 90 degrees from one point across the road to another pole 65 feet away (for example). Then if I could take these points and load them into Arc GIS as points to snap to, where I could then use my staking application to draw the new lines on the map at these points.”

Yes, iCMTGIS PRO along with the EOS Sub-cm GPS receiver will enable you to achieve what you have in mind.

1. Data Collection

You can use the GPS – Collect function in iCMTGIS PRO to record the start and end points then create the Line Feature.

2. Line Stakeout

The GPS – Line Stakeout function in iCMTGIS PRO will help you stay on the straight line and display your distance from the starting point. This will allow you to set a pole at a specific distance from the staring point. The app also provides a function to let you store the position of the pole. There is a tolerance setting in the Stakeout function that will issue beeps and flash a “Target” message as long as you are within range.

3. Traverse and Point Stakeout

“Also it would need to be able to route me say 90 degrees from one point across the road to another pole 65 feet away (for example).”

The GPS – Collect – Traverse function in iCMTGIS PRO will let you occupy an existing point and create a new point based on distance and angle (bearing or azimuth). Then you can use the GPS – Point Stakeout function to help you get to the new point.

If that “other pole” already exists as an imported point, then you will simply use GPS – Point Stakeout to get to it.

In fact, I would incorporate the point representing that other pole or any other location in the Line Feature mentioned in Step 2 above. In other words, you would create your entire “route” as a single Line Feature (no matter how many bends there are) then use the Line Stakeout function throughout.

4. Digitization

You can draw Points, Lines and Areas within iCMTGIS PRO. You can export these Features to Shapefiles to use in other apps. You can also import Points, Lines and Areas from Shapefiles.

“Would one of your less expensive apps do some of the tasks I talked about in my first email just to try it out?”

The Stakeout iCMT app is very cost effective for performing the point and line stakeout tasks. What it does not provide, among others, are the GPS – Collect function and the GPS – Traverse function. In addition, it gets the GPS position from the Apple CoreLocation, which is not as accurate as the GPS position that iCMTGIS PRO gets directly from the EOS GPS receiver in the “Enable External GPS receiver” mode.

The Stakeout iCMT app will be great to use for a practice run of your stakeout operation or for training your employees.

Stakeout iCMT for trailblazing

“I’m wondering if your software has the capability to allow a user to navigate to a location based on a set of coordinates. . . . The problem is that ArcPad is not designed to allow users to navigate to a set of points and I cant find anything else that will easily allow a user to do this, either. Through internet research, I discovered a reference to your iPhone app Stakeout iCMT. Before I recommend a purchase for this, could you tell me some more about the product? Will it show the tractor driver the location of the next point in our shapefile so that he would see distance and direction to get within 10-15 feet of that point? Please note the driver will NOT have to collect any data in the field he is merely using the program to show him how to drive the tractor in order to create a walking trail (which is NOT a straight line) through dense terrain.”

Stakeout iCMT will allow a user to navigate to a location based on a set of coordinates. It can also help the user to stay on course on a design line.

Stakeout iCMT can be used on an iPhone or an iPad. The iOS devices do not provide good GPS accuracies. You could use an external Bluetooth GPS receiver that is compatible with iPhone or iPad, such as a Bad Elf GPS or a Dual XGPS-150A, which claim 1-3 meters accuracy. There are more accurate GPS receivers available, which cost much more.

Stakeout iCMT is probably the least expensive but really powerful software solution for your task at hand. You can import your Shapefiles then use Stakeout iCMT in one of the following ways:

1. If you want the driver to go from one design point to the next, then create a Line Feature by using Add Line Manually and snapping to the points in the desired order. Then use Line Stakeout to go from one node to the next on the line shape.
You can set the distance tolerance for the app to notify you when you get within that distance from the current target point.

2. You could import the Line shape for the desired path through the woods. Then you would use the Line Stakeout function and let the app help you stay close to the line all the time. The Line Stakeout function will display your distance to the line all the time. And if you set a distance tolerance, then the app can keep on beeping as long as you are within the tolerance distance from the line.

We also have several other apps that incorporate the Stakeout functions along with other functionality.

Off-line GPS data collection

“I would like the ability to collect points, lines, and polygons in the field, offline, with a way to easily download them as shapefiles for use in ArcMap when I return to the office. Will I need to purchase anything else in order to do what I have indicated?”

iCMTGIS II and iGPSGIS II will let you collect points, lines, and polygons in the field, offline, and you can download them as Shapefiles for use in ArcMap when you return to the office.

As far as off-line GPS/GIS data collection and Shapefile import/export goes, iCMTGIS II or iGPSGIS II is all you need.

The questions is whether you need to have a background map displayed as reference while collecting GPS/GIS data.

When you have connection to wi-fi, you can have the standard or satellite Apple Map displayed as background map.

If you have Shapefiles for the region in which you will be collecting data, you can import those into iCMTGIS II or iGPSGIS II as off-line background reference.
If you need to have an off-line geotiff background map displayed during data collection, then you will need to get the PC-GIS 09 mapping software, which will convert geotiff images to the .pim format for use with iCMTGIS II or iGPSGIS II.

Which app will help me layout drain tiles based on Shapefiles?

If you just wish to import Shapefiles and locate the points, lines or areas displayed on your iPhone or iPad with GPS, Stakeout iCMT will help you accomplish the task.

Please also read a few relevant previous blog posts:




Have a Happy New Year!

I need my zone map to display in color


Shapefiles don’t store information about how to render the shapes in different colors and fill patterns. Therefore, when you export your zone map in Shapefiles format then import it into Farming GPS GIS, Forester GPS GIS, iCMTGIS II or iGPSGIS II, the default solid green color will be used to represent all Area Features.

If you have PC-GIS, you can classify the grids based on a variable (Attribute) and obtain a color zone map. Then you can save the data in the .pmp job file format to open in Farming GPS GIS, Forester GPS GIS, iCMTGIS II or iGPSGIS II.

PC-GIS will also let you prepare a raster image file for use with iCMTGIS II or iGPSGIS II as a background map.  Currently, Farming GPS GIS and Forester GPS GIS do not provide this capability but can use the built-in wi-fi-dependent Apple Maps as background.

Loading shapes into multiple iPads

“I am importing farm shapefiles. Can I share this info with another iPad or do I have to import them into each iPad seperately. I am moving hundreds of shapefiles into Farming GPS GIS, and I need to load several iPads. So, any solutions to save time would be very valuable.”

After you have imported one or more Shapefiles into the currently active job in Farming GPS GIS, you can save that job as a .pmp file. The .pmp file will contain all the Features imported from the imported Shapefiles.

You may copy the .pmp file to your PC then copy it to another iPad running the Farming GPS GIS app. All the Features will show up on the second iPad.

In this way, you can import all the Shapefiles into one or more jobs saved as .pmp files on one iPad and “clone” the same set of data for each of the other iPads by copying the .pmp files to those iPads.

This method applies to iCMTGIS II and iGPSGIS II as well.