Why are proper cartographic skills essential in working with UAS data?
Without context in an aerial image, it’s difficult to process what exactly you are looking at and what you are trying to recover from the image itself. Even when adding a North arrow and scale, the UAS data within the map becomes more useful.
What are the fundamentals of turning either a drawing or an aerial image into a map?
First, a reference scale should be added in order to get an idea of how big the area you are looking at is. A north arrow should also be added to have a sense of direction. A locator map can also help with a broader context of the area of interest.
What can spatial patterns of data tell the reader about UAS data? Provide several examples.
Spatial patterns of data can tell the reader about possible future exploration or a decrease in crop yield. Some examples include using certain sensors to detect economic mineral deposits similar to using geomagnetic surveys. Another example may include obtaining the soil moisture content in a farm field to increase the farmers yield.
What are the objectives of the lab?
The objective in this lab is to learn how to create good maps with UAS data within GIS software to further analyze and use the data. This lab also includes learning the difference between DSM and DEM, and how to create a map from an aerial image using fundamental map-making processes.
Methods
First off, opening up the DSM and
Orthomosaic into ArcMap is necessary so they can be used to create the final elevation
map. After the DSM and orthomosaic are brought in, use the hillshade tool by
searching “hillshade tool” and apply it to the DSM. Finally, create the map with
the fundamentals of a map-making such as including the north arrow, scale, legend, etc.
Figure 1. DSM and Orthomosaic of a sports-field in western Wisconsin showing elevation
What is the difference between a DSM and DEM? The difference
between a Georeferenced Mosaic and an Orthorectified Mosaic?
The difference between a DSM and a DEM is
that the DSM is a Digital Surface Map while a DEM is a Digital Elevation Map. A
DSM has numerous values included for the elevation while A DEM only has the
ground surface to create the raster. A georeferenced mosaic takes an image with
an already known coordinate system using ground control points to secure the
image while an orthorectified mosaic takes an image and accurately adjust it by
stitching together tie points using the computer so the image has a known
coordinate system.
What are those statistics? Why use them?
The statistics for the DSM are important because it shows all of the data used for presenting on a map such as the values of minimum and maximum ground elevation.
Metadata:
Platform: DJI Phantom 3 Advanced
Drone Sensor: Sony 16 Megapixel Camera
Altitude: 60 meters
Coordinate System: WGS1984 UTM zone 15N
Projection: WI State Plain
Date: March 7, 2016
What types of patterns do you notice on the orthomosaic?
On the orthomosaic there is a noticeable gradual slope increase from southwest to northeast. There is also a straight line of trees on the west side of the map that run north and south.
What patterns are noted on the DSM? How do these patterns align with the DSM descriptive statistics? How do the DSM patterns align with patterns with the orthomosaic?
On the DSM, there is a line pattern that resembles what would be the elevation on the map. These patterns on the DSM align with the statistics that have shown the values in elevation. Other patterns that line up with the orthomosaic are the trees, building, and other vegetation.
Describe the regions you created by combining differences in topography and vegetation.
The regions included a topographical high and low based on the higher elevation in the north, and the lower elevation in the south. The vegetation is separated into two so that it would not be a problem for everything else in the map.
What anomalies or errors are noted in the data sets?
In these data sets, there are no ground control points to stitch the parts down to the basemap. Other errors or anomalies include variable elevation numbers that could be off due to the trees reaching higher up and how the image was taken.
Where is the data quality the best? Where do you note poor data quality? How might this relate to the application?
The best data quality is towards the middle of the image because this is the area where its being stitched together. The poor data quality lies in the upper left corner of the image but could most likely be resolved by obtaining more data from that area.
Conclusion
Summarize what makes UAS data useful as a tool to the cartographer and GIS user?
UAS data is very useful when it comes to high quality data and solving problems for the cartographer and GIS user. It can display high levels of accuracy in a short amount of time.
What limitations does the data have? What should the user know about the data when working with it?
The downfalls are that in order to obtain this data, there must be good weather with low wind speed in the environment you are working in. Also when the user is working with the data, the program may not have the correct values when it is processed.
Speculate what other forms of data this data could be combined with to make it even more useful.
Another form of data that this could be combined with is ground control points so that the data can be stitched and tied down even better than if it was only the platform.
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