Fire Mapping in Google Earth. Accurate, efficient, cost effective wildland fire mapping from a fixed wing platform.

Transcription

1 Fire Mapping in Google Earth Accurate, efficient, cost effective wildland fire mapping from a fixed wing platform. Matthew Snyder July, 2015

2 Introduction 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.

3 Method #1 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. Photo Collection 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. Unneeded 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.

4 Application 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 Ten fires were mapped during the above flight with minimal turns over the fires. 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 or higher. Full use of this app is beyond the scope of this document, but I will describe the process for exporting photos.

5 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 will appear. 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 newest version. 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 Sharing. Under the DATA menu select Custom and chose your Photo Library layer. Under the MEDIA SIZE menu choose Small x768. This saves space on file size and makes them much easier to view in Google Earth. 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 pop-up window. 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

6 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: _1300_599_FireName_Perim_YourName. Entering the date in this format will keep it somewhat in line with GIS standards for export to ESRI ArcMap. 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 polygon. 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.

7 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 work with. 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 from

8 Method #2 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. Photo Collection 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. Application 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.

9 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 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.

10 Conclusion 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.

11 Glossary 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 and license code. Just enter your 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

12 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