Using mobile apps to add to the iMapInvasivesmap
Fairfax Tree Rescuers PRISM
Updated 6/15/2025
Note: When you have made your first observations, please email us so we can check to make sure that you had everything set up correctly for us to be able to use the data.
Before trying out the apps, please try the web-based version. You need that to create your account.
You might think that the apps are the easier way to go. In fact, there are enough tricks and limitations to both of them that you may find that for some of the work, it is easier to just use your phone to take photos and do the mapping from a computer at home. Note that if you click on “info” for a photo that you have added to Google Photos, it gives you a map with a marker for where the photo was taken.
There are two apps:
The two apps are equally easy to use once you have them set up.
- The iMapInvasives app is easier to set up. However, it only allows you to drop points - you can’t draw polygons or lines - and you can’t enter any details other than the very basic ones. Therefore, the way to use this app if you need anything more than that is to drop points in the field to mark locations then draw maps and add other data when you get home to your computer.
- The Survey 123 iMapInvasives app is more complicated to set up but allows you to draw polygons and lines in the field and enter other data. .
Minimum requirements for every survey:
- You must have Organization 3363 (Fairfax Tree Records) noted so we can see your data.
- A point, polygon, or line indicating the location of the invasive plant. For large infestations, polygons give more useful information, so please use them whenever possible. If you are using a point, make a note about the approximate size of the affected area.
- Presence Records
- The name of the species
- At least one clear photo. Ideally, include a photo that shows the extent of the infestations as well as 1-3 photos that allow reviewers to confirm the identification. When photographing the extent of the infestation, you might want to designate a location where you can include a landmark (or even place a marker) and return year after year to see progression.
- Distribution and (for polygons) Percent Cover
Optional but very helpful
Project numbers. This is how we filter to find your work and create reports. Let us know which projects you might use so we can sign you up.
Document one species in a location at a time!
As a rule, it’s best to create one record for each species in a given location. Although the app allows for adding more than one species per location, it can be cumbersome and can cause data errors. If you are noting a “severe infestation” using a Project number (see below) and multiple species are present in one severe infestation, such as trees blanketed by vines, create a record for the most dominant species and use the comment blank to note other species.
Simple ‘iMapInvasives’ app
(Useful only for marking a location with minimal details. In many cases, you will need to add more details later by going to the web version.)
First set up your account and practice using the web version.
- Make a note of your login information. You will need it for the app.
Then follow the instructions for the app in the Severe Infestation Surveys document.
Go to the App store and download iMapInvasives.
More comprehensive ‘Survey 123 iMapInvasives’ app
This polygon-enabling app is quite good, but it does take a while to get the hang of it. The confusion arises when you don’t realize the distinction between mapping two or more species in the same area versus mapping them in separate areas. When you first try it, you are best off starting over for each observation instead of lumping them into one.
First set up your account and practice using the web version.
- Make a note of your login information. You will need it for the app.
- Make a note of your ‘Person #.’ To find your number, go to https://www.imapinvasives.org/, then go to the dropdown on the upper left and click on Your Account. Your number is just above ‘First Name.’
Go to the App store and download the ArcGIS Survey123 app (as opposed to the other app called iMapInvasives).
This is complicated - but worth it! Carefully read and follow the instructions on Page 1 of this document (Steps 1 and 2) and take a look at the other pages. Note that once you download Survey123 to your phone, you will need to go to this URL - https://arcg.is/vfeTW - and click on ‘Open in the Survey 123 field app.’ (You could email the URL to yourself ahead of time so it will be handy on your phone).
Note that when you first open the app, it has a sign-in form for ArcGIS. Ignore that and “continue without signing in” there. Click on the iMapInvasives icon.
Log in, click on “Collect,” and fill out the basic info fields.
Enter these codes
- Your Person ID
- iMapInvasives Organization ID - 3363
- iMapInvasives Project ID (see codes below)
Although it says that the organization and project names will appear after you enter the numbers, they won’t - so don’t worry about that.
Set up your favorites
This is an optional step, but helpful if you plan to use the app more than once or twice. Go to the top right of your screen and select the three lines (menu). Then click “Save as favorite answers”. Then click on the X in the upper left corner. When you do any observation after that you can click on the Paste Answers from above to automatically populate this information in your new observation record. You may need to change the Project ID code, but other than that you should be set to move on to your observation.
Write down the three ID numbers (your ID, Organization ID, and Project ID) somewhere on your phone in case you need them again in the future. Always make sure those numbers are entered any time you use the app in that location (and be sure to change the Project code if you are mapping somewhere else).
To create a survey
Open Survey 123
Continue without logging in
Click on the iMapInvasives icon
Select “Paste answer from favorites” using the three bars in the upper right.
Change or enter the Project Number (see below) (or leave it blank)
Choose between Simple (a single point) or Advanced (polygon)
If Simple (meaning you just want to drop a point)
- Drop the point under “Searched Area.” If there is a map there already, X it out.
- If you are standing at the point, use the icon on the left to drop the point.
- If you are not standing at the point, use the map-like icon on the right to move the blue marker, then click on it, then hit the check mark on the lower right.
- Presence Records
- Present Species - pick one
- Photos - at least one clear photo that identifies the species
- Plant Fields
- Distribution
- Percent Cover Fields - Take your best guess. Don’t forget that this is the percentage for the entire searched area, which might include playing fields or other areas that aren’t natural.
If Advanced (meaning you want to draw a polygon)
- Searched Area, Create searched Area Polygon. (If there is a map there already, X it out.)
- Use + or - to Zoom in or out
- Click the polygon icon (lower left)
- Tap around the screen to draw your polygon. You don’t need to close the loop. (See below for some tips on creating polygons.)
- Tap the icon/check mark lower right.
- Presence Records
- If choosing a polygon, you have the option to click “yes” to use the same Searched Area Polygon from previous entry
- Present Species - pick one
- Photos - at least one clear photo that identifies the species
- Plant Fields
- Distribution
- Percent Cover Fields - Take your best guess. Don’t forget that this is the percentage for the entire presence polygon, which might include playing fields or other areas that aren’t natural.
How to draw a polygon using the Survey123 mobile app
Draw By Hand:
This takes some practice. Just erase it and start over if it isn’t right.
- Tap on the polygon icon (lower left). Tap on the screen around the border of the area and drop as many points as you need to draw the shape the best you can.
- You don’t need to tap on the first point to close the loop. It closes itself.
- Once you are satisfied, click on the lower right-hand corner to finalize it. Click again on the check mark.
Walk the perimeter and have the app draw for you:
- The app was also designed to help you draw the polygon by walking the area. Using the track icon (to the right of the polygon icon) may be more precise if you have a really good signal and can walk the boundary of the infested area. If you can get most but not all the way around, this will still work.
General
- You can zoom in and out using the + and - on the right.
- Be sure to check off whether the searched area is the same as the observation area.
Project numbers: All but the last four ‘projects’ (tags) are used to indicate property ownership. The last four are for severe infestations. Since on the mobile app you can only enter one number, prioritize the severe infestation projects. You can edit the survey later from the web page to add more tags.
- 1625 VDOT rights of way - all
- 1626 VDOT rights of way - inaccessible to volunteers
- 1634 City of Fairfax Parks
- 1633 Clifton, VA parks including CBA
- 1629 Commercial properties
- 1630 Fairfax Board of Supervisors land
- 1635 Town of Herndon parks
- 1637 Town of Vienna parks
- 1640 Faith communities
- 1636 Falls Church, VA parks
- 1627 FCPA properties
- 1632 FCPS (Fairfax County Public Schools)
- 1628 HOA common land
- 1631 Multi-dwelling unit common land
- 1638 NOVA Parks
- 1639 Single family home properties
- 1642 National Park Service (NPS)
- 1643 Military
- 1644 Railroad rights of way
- 1645 Federal lands
- 1646 State parks
- 1647 Severe vine infestations
- 1685 Severe tree infestations
- 1686 Severe shrub infestations
- 1687 Severe ground-level infestations
- 1690 Search for severe infestations
- 1692 Operation Stream Shield
- 1693 Severe invasive plant infestations