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.