Purchase Distance and Area Measure


Introduction
Polygon drawing example
Known limitations

Introduction

Measure buildings, roads, parks, land, countries, lakes, etc from a satellite view. Calculates distances, areas, and perimeters.

Features that this application offers that most competitors do not:
- add custom distance and area units.
- draw interior polygons
- draw interior polygons. For example, land area with bodies of water removed.
- add a point to the middle of a path (Most only allow you to add to the end of the path) Tap to add to the end of a path. Long press to add to the middle of a path.
- swap two points in a path or polygon.
- add your current location from GPS receiver.

Features:
- search by postal code, city, address, etc
- 3 map layer options
- export and import .kml files via Dropbox, iCloud, email, etc
- many settings can be changed on the map without having to enter settings
- pins are draggable
- name, notes, and color fields for each path and polygon
- email or text message path and polygon data
- lock map from scrolling and draw by dragging your finger (BETA. may be removed in future versions)
- four verbosity modes. See only the information that you want to see.

4 drawing modes:
- paths
- polygon
- polygon with hollow spaces inside
- no edit mode (to prevent accidental edits)

Values displayed for paths:
- total distance
- incremental distance for each waypoint

Values displayed for polygons:
- area
- perimeter
- distance for each side

Add points to a path or polygon in 1 of 4 ways:
- tap on the map
- use your current location
- enter coordinates manually (add point by another method and edit latitude and longitude)
- import .kml file

Default distance units include:
- kilometers
- miles
- nautical miles
- meters
- feet

Default area units include:
- square metres
- square feet
- square yards
- square kilometres
- square miles
- square nautical miles
- acres
- hectares

Coordinate formats:
- degrees
- degrees minutes seconds
- degrees minutes

Please note that loading satellite maps requires an internet connection.


Polygon drawing example

Drawing a polygon is more complicated than drawing a path. With a path, the newly added point is simply added to the end. When you click to add a pin to an existing polygon, the pin is added to the closest side of the polygon.
For this example, the goal is to draw a polygon that rougly estimates the area of the West African country of Mauritania.

Start by drawing a rough overlay of the entire area.
NOT like this:


Like this: (Note that you can always drag a pin after it is added)


Adding a new pin: (Green pin is the new pin)


Adding a new pin...


Adding a new pin...
Notice that the pin was added where we want it, but the line is not being drawn like we want it to be. Remember that the pin is added to the nearest line, which in this case was the Northeast border.


Clicking the trash button removes the troublesome pin:


Adding the pin to the correct line. Now we can drag the pin were we want to put it. To drag the pin, long press on the selected pin and it will raise above your finger so that you can see it. Then drag the pin and drop it on the desired corner of the border.


After the pin was dropped in the desired place:


Adding a new pin...
Again, notice that the pin was added where we want it, but the line is not being drawn like we want it to be. Remember that the pin is added to the nearest line, which in this case was the Northeast border.
EDIT: Note that you can swap pins in the same polygon by dragging one pin onto another pin. This single action would replace the next 3 screenshots.


Clicking the trash button removes the troublesome pin:


Adding the pin to the correct line. Now we can drag the pin were we want to put it. To drag the pin, long press on the selected pin and it will raise above your finger so that you can see it. Then drag the pin and drop it on the desired corner of the border.


After the pin was dropped in the desired place:


Adding a new pin:


Adding a new pin:


Adding a new pin:


Adding a new pin:


Adding a new pin:


Adding a new pin:


Adding a new pin:


Adding a new pin:


Changing verbosity to v3. Notice that the area and perimeter is displayed near the center of the polyon. The length of each edge is also displayed in smaller font.


If you have trouble reading any number because it is covered by a pin or line, you can spin the map using 2 fingers and a spinning gesture. To snap the map back to North equals up, you can switch to the list page and then back to the map.


(This screenshot was taken at a later date, which is why the numbers are a little different. Rotating the map did not change the values.)

Known limitations

  • Interior polygons should not overlap. Overlapping interior polygons will result in incorrect area calculations.
  • Interior polygons should be completely inside their parent polygon. User will get a warning if when trying to add a point for a polygon outside of its parent polygon. However, it is possible for a user to alter the polygon's outer boundry so that some of the interior polygons are outside of the outer boundry.
  • (Very unlikely) If drawing a polygon with an interior cutout (hollow space), that crosses the 180th meridian (the international date line), the perimeter polygon and all interior polygons that cross the 180th meridian must make their first cross of the 180th meridian in the same direction.
  • The distances, areas, and perimeters of paths and polygons are only calculated on the map. This means that if you import a .kml or .kmz file on the list page, the distances, areas, and perimeters of the imported shape will be 0 until you switch to the map and back.
  • Interior polygons cannot have their own interior polygons. For example, in the Central Park example with the lakes removed, islands in lakes cannot be included.