Building Maps Using UAS Data

Introduction

Why are proper cartographic skills essential in working with UAS data?

                Without proper cartographic skills, UAS data will be useless. If you do not include things like north arrows or scale bars, the data will not make sense to the reader. The data needs to contain sources and your name so people know the creator of the map

What are the fundamentals of turning either a drawing or an aerial image into a map?

                This includes properly scaling and locating your map. A locator map will help orientate the reader. A north arrow and scale bar are also essential to produce a good map.

What can spatial patterns of data tell the reader about UAS data? Provide several examples.

                Spatial patterns can help a reader determine manmade objects from natural objects. They can help determine agricultural patterns and determining quality of the crop and how to improve the yield. You can use it geology to distinguish elevation changes and where potential geologic units are. You could use spatial patterns to determine deforestation rates in logging areas.

What are the objectives of the lab?

                The goal of the lab is to learn how to use UAS data to make cartographically correct maps in GIS. The map must be correctly labeled and scaled so the data makes sense. The lab will show us how to transfer the UAS data into Arcmap and how to correctly process it.

Methods

What is the difference between a DSM and DEM? What is the difference between georeferenced mosaic and an orthorectified mosaic?

                DSM (digital surface model) will show elevation for any surface feature located in the mapping area. This includes trees, vegetation, cars, people, roads, etc… DEM (digital elevation model) only shows the elevation of the ground feature and will not include trees or buildings. http://gis.stackexchange.com/questions/5701/what-is-the-difference-between-dem-dsm-and-dtm

                Georeferenced mosaics are more accurate then orthorectified mosaics. Georeferenced mosaics reference set ground control points. These GCPs have been placed accurately and are recorded. The orthorectified points from the UAS itself. These points have greater vertical and horizontal inaccuracies.

What are the statistics? Why use them?

                The statistics give you the maximum and minimum and average elevations which is useful because it will give perspective and a better reference.

How did you hillshade the DSM? Delineate regions of the DSM, thinking of each region in terms of topography, relating that to the vegetation.

                You need to search for the hillshade tool and make sure you have spatial analysis on. You then select the input raster and give a name and location for the output raster. You can also set the azimuth and altitude of the sun. You then let the tool process the data and get a map like this. You can delineate areas where there is a tree line running alongside the track.  

Results

What types of patterns do you notice on the orthomosaics.

                There is a distinct tree line on the west side of the track. You can clearly see the manmade features, road and track.

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?

                You can clearly see the elevation but can’t see the tree line as distinctly until you use the hillshade tool. The statistics allow you to tell the elevation range and give you a better perspective. Together they both give a good picture of the area. You can tell the elevation is increasing to the northeast so if you were running on the track heading north, you be moving up hill.

Describe the regions you created by combining differences in topography and vegetation.

                I created areas for vegetation where the tree line lies. I also created a north and south section to distinguish the difference in elevation.

Errors in Data

                The elevation said 22 meters and the elevation in Eau Claire is about 240 meters. There are also parts of the map that are cut off that could be useful data.

Best Data

                The best data seems to fall in the middle and the poor quality data seems to be at the edges where there are abrupt cut offs.

Conclusion

           
    UAS data is useful because you can take imagery quicker and more efficient with higher quality resolution dependent on sensors. The data can be easy to transfer over to GIS. UAS data also high accuracy when used correctly. If one use a UAS with many GCPS you can created a very accurate map. If the GCPs were not accurately set the data could be inaccurate. The user must know which sensors are being used and how the pilot collected the data to make sure it is accurate. A UAS is limited by weather and light conditions and on board sensors. A user could combine UAS data with survey data to make accurate maps. They could combine both the ground and aerial views.