After uploading your data to PrecisionMapper our processing engines stitches your individual pictures together to develop georeferenced 2D and 3D outputs in several file formats. Certain outputs will be viewable in the PrecisionMapper web viewer while others may need to be downloaded from the site to analyze in other software. To understand the technical details of each output type and where to view them see the PrecisionMapper Outputs section of the knowledge base.
Below we have reviewed every type of data available through the PrecisionMapper system and some strategies to making this data useful in your analysis.
The PrecisionMapper Web Viewer
Within PrecisionMapper all the data you have uploaded will be archived in the cloud and available at any time by logging into your PrecisionMapper account. Datasets are organized on your Surveys page based on the date that the survey was flown.
Once you select a Survey from your surveys page you will see the data within our online viewer. To the left of this viewer you will see all the processes that have been run against this source data. As you select these processes from the left bar they outputs will appear in the Web Viewer depending on whether they are compatible with the online viewer. Some data sources must be pulled into an external software for full review.
The Web Viewer itself has several features that can be used for analysis of your data online. Below we have covered each of the features of the web viewer.
- 2D Viewer- The default view of the web viewer is the 2D visualization of the data. This will display the Orthomosaic Tiff 2D version of your processed data.
- 3D Viewer- The 3D viewer is only active if you have selected “3D outputs” to be processed during your upload process. When present the 3D model is displayed in the 3D Viewer.
- Drop a Pin- Users can drop a georeferenced pin on your imagery that will be saved alongside the project. These pins can be labeled by the user.
- Select an Area- Measure an area of your 2D products by using the “Select Area” feature. This will measure any polygon designated by the user in Hectares.
- Change Image Opacity- Image opacity can be changed within the viewer to give your map a look of transparency if needed.
- Web Viewer Basemaps- The basemap can be changed from Satellite Imagery to Hybrid street map for your analysis.
2 Dimensional Outputs
The primary 2D output is the orthomosaic. This can come in two different file formats- GeoTiff and KML.
The Web Viewer of Precisionmapper can handle this orthomosaic for viewing purposes. But you are still limited in zoom levels when compared to viewing the outputs in a local software on your computer.
Pulling the data to another local software also give you the chance to overlay other data layers to assist in your analysis.
The KML version of the Orthomosaic is a file type made for Google Earth. This program is freely available and will give you some additional functionality with the data. However you are still limited in comparison to a full GIS software. To understand the steps of viewing a KML within Google Earth see the Google Earth section under Exporting Data in our knowledgebase.
The GeoTiff version of the 2D outputs is the primary piece of data that people are interested in. This is a fully detailed birds eye view of your area of interest. The Geotiff can often be opened in a standard photo viewing software but you still lack the functionality of a full GIS or Remote Sensing software with this data type. A free GIS software that we often recommend is QGIS. Below we have covered some basic operations in the QGIS software for dealing with your 2D outputs. For further information on this topic see the QGIS section under Exporting Data in our knowledgebase.
Opening and overlaying your 2D data in QGIS-
1. Open your GEOTiff Orthomosaic available for download on precisionmapper.com. This is done by navigating to going to “Layers” in the main tool bar- “Add Layer”- “Add Raster Layer”. Select the .tif output that is packaged with your Georeferenced image output.
2. Now that you have the Orthomosaic opened in QGIS you have full zoom capabilities for simple viewing of your orthomosaic. If you would like to take it a step futher you can also overlay related datasets in the software.
3. In this example I am adding my Volume Estimation shapefile layer onto the QGIS map. The Shapefile is considered a “Vector” layer so this time I will go into “Layers” in the main tool bar- “Add Layer”- “Add Vector Layer”.
4. Shapefiles are made of several connected file types. So when you navigate to this to add the layer you will see a package of files within your shapefile output. Select the version that has .shp file type to get this added to your data frame.
5. Once you have opened this shapefile it should overlap on top of the data currently in QGIS. If it does not you can use the “Layers Panel” on the right side to re order the layers deciding which appears on the top of the overlay.
6. QGIS has many tools that can be used to analyze and interpret your data. For a full lesson on QGIS and its functionality check out the online documentation for this software https://docs.qgis.org/2.8/en/docs/user_manual/introduction/getting_started.html
3 Dimensional Outputs
The 3D outputs of the PrecisionMapper can be very useful for analysis of terrain or buildings. Within precisionmapper.com you can view the 3D model output of your project if 3D outputs were selected during the upload process. This is a simple view of your dataset with elevation values accounted for in the 3D view.
3D outputs of PrecisionMapper include- Triangle Mesh, Point cloud las, Digital Surface Model (DSM), and the 3D model . Each of these file formats have a slightly different version of the 3D data represented. See PrecisionMapper Outputs section of the knowledge base for detail on each.
To gain a little more functionality from your 3D outputs you may consider pulling the data to an external software can be useful. Below we have gone over the steps to open and measure your data using the free Quick Terrain Reader software available online.
1. With Quick Terrain Reader opened select the Folder icon in the upper left corner to open a 3D file. This software is compatible with the .las point cloud as well as the DSM output of PrecisionMapper. In the example below we are opening the .las point cloud file.
2. Once you have opened either the Point Cloud or DSM file outputs within the viewer you will see the elevation values represented on screen in the Quick Terrain Reader.
3. There are a few basic tools that can be useful in the Quick Terrain Viewer. The “Model Information” tool can give you a quick view of the elevation distribution in your dataset along with other useful statistics. Choose the Model Information Icon from the main tool bar to view this report-
4. Another useful tool is the measurement tool. This can be used to measure horizontal and vertical distances between features in your 3D view of the data. To use this feature you will select the “Start Mensuration” tool from the main tool bar. Click on the start and end points of what you want to measure and you will see a distance appear at the top of the measuring bar within the viewer.
5. To explore more features within Quick Terrain Reader check out their tutorials page- http://appliedimagery.com/tutorials/
We have many Vegetation Indices that we offer across any type of sensor- RGB, BGNIR, RGNIR, and multi band data. The primary output of each VI is a 2D representation of the data as a GEOTiff or KML file type. Similar to the 2D Outputs section of this article you will open the KML in Google Earth and the GeoTiff in any GIS or Remote Sensing software for analysis.
Here we will provide a more general description of Vegetation Indices and what they actually mean. For a detailed review of each particular Vegetation Index see our Algorithms Overview Section.
What is a Vegetation Index?
A Vegetation Index is a spectral calculation that is done between two or more bands of the source data designed to enhance the contribution of vegetation properties and allow for comparisons of photosynthetic activity across your area of interest.
When the VI calculation takes place, it goes pixel by pixel through your entire dataset and runs a fairly simple calculation on the spectral values of that pixel. This will assign a value representing some version of plant health for each pixel in the image. These values are then generalized to different ranges and turned into the colorized map you see on screen when the calculation is complete.
VI’s allow you to see relative differences in the general plant health across your entire field. The methodology behind these calculations are slightly different for each VI that we offer. But generally these calculations are leaning heavily on the Green and Near Infrared bands of the data it is derived from. These bands can tell us a lot about how healthy a plant really is.
Below we have gone over some tools that can be used to analyze your Vegetation Index data outside of the PrecisionMapper web viewer. Similar to 2D outputs the primary tool for this is also QGIS.
1. Using the GeoTiff output of the Vegetation Index open the Raster file within the QGIS software. This is done using the same methods explained when opening a Orthomosaic in QGIS in our 2 Dimensional Output section.
2. Once you have this opened you will first notice that the coloration of the file is very different from the online viewer. All the same values are present but the color ramp assigned to these values is Black to White instead of Red to Green.
3. You are able to change the color style of this map by changing the “Properties” of the layer. To do this right click on your layer in the “Layers Panel” on the left side, go to “Properties”, and go into the “Style” menu.
4. Under “Render Type” you can select “Singleband Pseudocolor” in the dropdown. From here you will be able to alter the color ramp associated with the dataset. Within the “Load Min/Max Values” section there is a “Color” setting that you can change to any color scale you like. In my example I am changing it to a similar Red to Green style seen in the PrecisionMapper viewer.
5. By following the same workflow mentioned in the 2 Dimensional Outputs section here you can overlap other sources of data from PrecisionMapper or other external sources.
6. For a full review of QGIS and its capabilities check out their documentation page- https://docs.qgis.org/2.8/en/docs/user_manual/introduction/getting_started.html