Fire Mapping in Google Earth™ - Amazon S3 · Fire Mapping in Google Earth™ ... Mapping is done...
Embed Size (px)
Transcript of Fire Mapping in Google Earth™ - Amazon S3 · Fire Mapping in Google Earth™ ... Mapping is done...
Fire Mapping in Google Earth™
Accurate, efficient, cost effective wildland fire mapping from a fixed wing platform.
In this document I will describe several methods for mapping wildland fires from a
fixed wing platform in a way that minimizes flight time over the fire. This will
reduce fuel cost and hazard exposure as well as make aerial mapped perimeters
more accurate. Mapping is done on the ground in a digital format that is easily
transferred into ESRI ArcMap for producing conventional paper maps.
Historically, large remote wildland fires have been mapped by an Aerial Observer
hand drawing fire perimeters on USGS Topo Quads. Mapping is done in the air
over the fire by flying numerous laps around the fire while the mapper draws in
what they see. This takes time and fuel and can be hard on the mapper due to the
possibility of motion sickness.
Perimeters are also collected from rotor wing platforms using a “GPS Sharpie”
method. This requires a much more expensive helicopter flight taking a GPS track
log. The pilot is required to slowly fly the entire perimeter at low level while
performing complex maneuvers in order to catch all fingers. This method takes
significant flight time leading to increased costs and increased exposure to
associated hazards. As well, accuracy is defined by the skill of the pilot.
Methods described use an Apple iPad™, but can be easily replicated with a regular
digital camera, GPS, and second computer monitor.
In this method, called Photo Rectification, mapping is performed by comparing
aerial photography to landscape imagery in Google Earth and drawing in the fire
perimeter as a polygon. It is very important that you have enough quality imagery
encompassing the entire fire perimeter.
Use of a GPS track log is advised but it is important to realize and pass on to your
pilot that you are not mapping using the “GPS Sharpie” method. Your GPS track
log will not be used for the perimeter. It is merely a broad reference for your
location when the photos are taken.
In drawing your perimeter in Google Earth you will be referencing the fire
perimeter to terrain and vegetative features. The more unique features you can
reference outside of the fire the better. In order to achieve this you will need to
have significant altitude and distance from the fire. I have successfully mapped
fires from as high as 16,000 feet to get the whole fire in the frame, but 4,000 to
5,000 feet AGL is usually a good altitude to aim for. A good rule of thumb is to
look for about a 45° angle. 5,000 feet up and 5,000 feet out from the perimeter
works well. Remember, you are not flying the perimeter and it is more important
to capture the unburned areas around the fire than the fire itself. Features to look
for are streams, ponds, meadows, and any change in vegetation, etc. The more
distinctive features in a single photo, the easier it will be to align and reference it
in Google Earth. You will want about 10% of the photo to have fire and 90% the
area around the fire. Take photos from multiple directions. Take lots of photos.
You will want plenty of overlap between photos. You cannot have too many. Un-
needed photos can be deleted later. Having to re-fly a fire to get missed imagery
is fairly counterproductive. Sufficient photos should be collected in one pass
around the fire.
I use an Apple iPad for all my mapping. The iPad has a decent camera which uses
a built in GPS to geo-reference photos taken so you will know where each photo
was taken from. This will aid you in gaining a point of reference when drawing
them in Google Earth if you don’t have easily recognizable features in the frame.
As well, the large, high definition touch screen makes it easy to zoom in on areas
of interest in your photos.
I use an app called GPS Kit by
Garafa to keep a track log in the
background while I am taking
pictures with the stock Camera App.
Tracks can then be exported from
the app in .KML format and loaded
in Google Earth. If an iPad is not
available, tracks from Garmin GPS
units can be easily imported into
Google Earth. Tracks are saved in
.GPX format in newer GPS units. For
older units such as the 60CSx and
eTrex, tracks can be imported into
Garmin MapSource and saved as a .GPX. Google Earth has built in support for
these files. Simply drag and drop them anywhere on the map in Google Earth
from an Explorer window. Tracks are saved in internal storage in the
x:\Garimn\GPX directory. Remember to first save them somewhere on your hard
drive if you want to use them once you disconnect the GPS.
Individual photos can also be imported as waypoints using a free app called
Avenza PDF Maps. Some options have changed in the app so make sure you
update to the most recent version 2.5.1 or higher. Full use of this app is beyond
the scope of this document, but I will describe the process for exporting photos.
Ten fires were mapped during the above flight with minimal
turns over the fires.
In order to get your photos into a .KMZ file you must have a PDF map of the fire
area. USGS Topo Quads can be downloaded from the Map Store within the app.
As well custom map sets are available for most areas.
Select the map and use the wrench button to pull up the Tools menu.
Tap Plot Photos and tap on the photos of the fire that you just took. Only
photos that are geo-referenced in the bounds of the map you have loaded
Tap to select the photos of the fire and tap the Done button when finished.
You will see your photos placed on the map as red pins. In earlier versions
there is a limit of four photos per import so make sure you update to the
Tap the Map Features button in the lower right corner of the screen.
Tap the Export button in the lower right of the pop-up menu.
Under the SEND TO menu choose iTunes File
Under the DATA menu select Custom and
chose your Photo Library layer.
Under the MEDIA SIZE menu choose Small -
1024x768. This saves space on file size and
makes them much easier to view in Google
Tap Export to finish and use iTunes File
Sharing to retrieve your .kmz file.
Load the resulting KMZ file into Google Earth and the photos will show up as pins
in their respective locations. Clicking on a pin will show the associated picture in a
Zoom in to the fire area in Google Earth using the imported GPS track and
imported photos as a reference. Click the Add menu > Polygon. This will bring up a
new polygon properties window. This menu must be open to add/edit the
polygon for the fire. Add a descriptive name with the fire name/number and the
date the pictures used to draw the perimeter were taken. Example:
20150718_1300_599_FireName_Perim_YourName. Entering the date in this
format will keep it somewhat in line with GIS standards for export to ESRI
Before you start drawing your perimeter, go to the Style, Color tab and set your
Line and Fill (Area) colors. For the initial drawing it may be easier to change the
Area drop-down from Filled+Outlined to Outlined. This will keep the fill color from
hiding areas while you are drawing. Alternately you can reduce the Opacity to a
level you can easily see through.
When drawing, find a photo with the fire perimeter near an obvious reference
feature. This may be a pond, a distinctive bend in a river, a meadow etc. Even in
areas of low resolution Landsat imagery in Google Earth you will be able to find
many of these features. Left clicks add points to the polygon, and right clicks
delete them. To add points in the middle of a line just select a point where you
want to begin adding and new points will be drawn from that location. Tilting and
spinning the camera to match your photos will make it easier to visualize where
the perimeter line should be placed. When you are done, click ‘ok’ to save your
If you need to edit the polygon, right click it in the menu and go to ‘Properties’. Be
aware that the draw direction may have changed. With practice you will be able
to quickly make fire perimeters from photos.
Sometimes photos need some modification in order for the black areas to really
stand out. The Photos app in iOS can do amazing things with a hazy photo. Simply
select the photo, hit Edit, and tap the magic wand tool. By tuning diffferent colors,
contrasts, and balances of your photos you can make your photos much easier to
Much of Alaska and remote parts of the Lower 48 are covered in low resolution
Landsat imagery. Photo Rectifying fire perimeters with this imagery can be
difficult and takes practice to do with any accuracy. Thanks to the University of
Alaska Fairbanks’ Statewide Digital Mapping Initiative (SDMI) there is often better
imagery available. The SDMI - Best Data Layer is a KML overlay that brings good
high resolution imagery to may parts of Alaska. The layer can be downloaded
In this method photos will be added to Google Earth as Image Overlays. This
“drapes” the photos over the terrain replacing the stock Google Earth imagery
with imagery of the fire. This may not be practical in all situations due to
smoke/weather conditions obscuring parts of the fire. Once the Imagery is in
place, drawing in the polygon is very fast and very accurate.
Photos must be taken from sufficient altitude to encompass the whole fire or
larger sections of the fire. Photos must have zero oblique, meaning they must be
straight down with no angle to them. While this may be nearly impossible in an
aircraft without a bubble window, this can be mitigated with an exterior mounted
camera taking frequent time-lapse photos. Some recognizable features must still
be present in order to align the photos with the background imagery.
Using the track import method described above, find the area of the fire in
Google Earth. In the Add menu click Image Overlay. In the window that pops up
click Browse and navigate to the desired photo. The original placement will likely
be much larger that it’s true size on the ground. Resize it by dragging on the sides
and corners, move it by dragging from the center cross, and rotate it by moving
the green diamond. Play with the Opacity slider to make the background imagery
visible through photo. Take your time stretching and spinning the Image Overlay
with the opacity reduced until everything lines up. Once complete take the
Opacity slider back to full and hit Ok. If the fire is too big to get in one photo just
repeat the above steps with multiple photos until you have the whole fire. The
perimeter can now be quickly traced over the new Image Overlay by adding a
polygon as described in Method #1. If the polygon is not showing up because the
Image Overlay is hiding it, you can raise it up by clicking on the Altitude tab in the
polygon properties and setting a specific height Relative to Ground instead of
Clamped to Ground. 1-2 meters is usually sufficient.
Conversion to ESRI ArcMap
Once you have a completed perimeter you will need to convert it to a shape file
format that is recognized by ESRI ArcMap. You will need DNR GPS which can be
downloaded for free from http://www.dnr.state.mn.us/mis/gis/DNRGPS/DNRGPS.html.
In Google Earth right click on the polygon you want to save in the sidebar and
click on Save Place As… You can keep the name you gave it when you created it or
give it a new one. Make sure you select the Save as type: as KML not KMZ. See the
glossary at the end of the document for the difference.
Load DNR GPS and click the File menu > Load From > File… Change the file type in
the lower right to Google Keyhole Markup Language (*.kml). Navigate to the file
you just saved and let it load. If you don’t see your file, confirm that you saved it
as .kml not .kmz in Google Earth.
To convert it click the File menu > Save to > File… Change the file type to ESRI
Shapefile 2D (*.shp) and give it a name and hit Save. In the window that appears
select Polygon and click OK. This step is very important as ArcMap does not easily
convert from lines to polygons. DNR GPS will automatically create the four
necessary files that make up a shapefile.
As technology advances, tools are being produced that will allow us to become
more efficient in our daily activities. Mobile devices such as smart phones and
tablets have the capability to provide us with a vast amount of information, at our
fingertips. Products are becoming available that were just not possible even a few
years ago. I feel that it is important, as an industry, to keep up with these
advances. This is just one way that we can achieve this.
DNR GPS – Windows PC Program
Windows PC program for loading data from GPS units and converting files
between several GIS standard file types. Example: ESRI .shp, Garmin .gpx,
Google Earth .kml, etc.
Google Earth Pro – Windows/Mac/iOS/Android program
Google Earth Pro is the more powerful and capable version of Google Earth
that has until recently required an expensive subscription. It has many extra
options over the standard version including showing measurements for
lines and polygons, native support for ESRI shapefile import, and improved
print and photo export resolution.
Google Earth Pro is now free. After you install and run it the first time it will
ask for your email and license code. Just enter your email and enter your
license code as GEPFREE.
GPS Kit – iOS App
Paid iOS App for recording GPS tracks and points. Data can exported in
multiple formats including KML and GPX. Developed by Garafa, LLC.
GPX – GPS eXchange Format
An Open XML language for storing geographic data for waypoints, lines,
and routes. Due to its open nature, any GPS manufacturer can implement it
without paying licensing fees.
KML – Keyhole Markup Language
A text based XML language for defining GIS location data for use in Google
Earth and many other programs. Data may include point, track, and
polygon data as well as photos, point descriptions, 3D models, web links,
etc. Files can be manually viewed and edited with any document viewer.
KMZ – Keyhole Markup Language - Zipped
A zipped or compressed KML file containing all associated images, icons,
overlays and 3D models.
Note: This is actually a .zip file. If you change the extension from .kmz to
.zip you can browse its contents like a normal .zip file. There will be a
doc.kml containing the normal .kml data and a \Photos directory containing
any photos associated with that layer.
PDF Maps – iOS App
Free iOS and Android App that uses a device’s internal GPS to show a user’s
location on a PDF format map. Points and lines can be created and
exported or imported on maps. Developed by Avenza Systems Inc.
SDMI – BDL – Google Earth KML Layer
University of Alaska, Fairbanks’ Statewide Digital Mapping Initiative (SDMI)
is a great source for good imagery in remote parts of alaska. The SDMI -
Best Data Layer (BDL) is a KML overlay that brings good high resolution
imagery to many parts of remote Alaska. The layer can be downloaded
from the Geographic Information Networks of Alaska (GINA) website at