Explore

AT 309 - Week 15 - Vertical Datums

Intro:

Geographical datums provide the foundational reference framework used to define precise locations on Earth’s surface. This makes them vital for all modern mapping and geospatial analysis. Datums help verify that latitude, longitude, and elevation measures are consistent and comparable. We were giving a random data set and tasked to identify what datums were used.

Steps:

To complete this lab we used the lab manual given to us by Dr. Hupy to help us. We started off in ArcGIS pro. Normally, the X-coordinate refers to the latitude axis, and the Y-coordinate refers to the longitudinal axis. However, when working with geographic datums, it is critical to remember that the X-coordinate is the longitudinal axis, and the Y-coordinate is the latitude axis. After I processed this file, I could confirm that the coordinates were flipped due to the result being a blank white map. We had to use the YXZ file for it to work properly.

To fully see the issue with the elevation value, I used the ArcGIS Earth software. In ArcGIS Earth, I uploaded the data file containing the YXZ coordinates. This software allowed me to view the GCPs but also visualize the terrain, relief, and view the elevation difference in the terrain. To test the Z value, I looked at the GCP point from the data file and compared it to the elevation value of an area near it. This was due to them having different 0 values.

To confirm the elevation difference, I used the National Geodetic Survey (NGS) Data Explorer. Using the NGS map, I looked up Bloom City and used geographic markers, like rivers and roads, to locate the correct marker. This datasheet contains critical information like the Orthomosaic height, GEOID height, model used, and more. I was able to calculate that difference was 26.423 meters

⁠

⁠

Want to print your doc?
This is not the way.

Try clicking the ··· in the right corner or using a keyboard shortcut (

CtrlP

) instead.