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Case Study: Aerial Mapping for Undeveloped Property in Crossroads, TX

We have been working closely with a few Architects in the Dallas Ft. Worth on conducting studies with drones on practical uses and applications. We will explain the process we go through, what we were able to capture and deliver to the Architect, how they were able to put this information to practical use, and what we learned for improvements on the next project. Here is an interactive 2D Map, 3D Map, and elevation study:

 

The Process:

Before we even fly, we have to get approval from the FAA for flights within restricted airspace. We filed for clearance flying up to 400′ in class B airspace. Using a DJI Phantom 4, we flew this 17 Acre property with an automated flight and imaging capturing process to provide more consistency. We captured 991 12 megapixel photos of the entire site. We flew at an altitude of 100′ and captured images with an 80% overlap, giving us the highest resolution models available. All of the photos are geo referenced and time stamped for proper processing. Once our field work is done, we go back to the office and start uploading all the captured photos and process our models for export.

 

Deliverable Exports:

Once processing is complete, we have access to digitally review 4 models and export to plug and play in CAD programs such as AutoCAD and Rhino. In this particular study, we used RHINO.

2D Orthomosaic Model- We can export between a 0.4- 8in/ pixel of resolution or quality. These are exportable in JPG or GeoTIFF formats.

Elevation Survey (as is with plants, vegetation, structures, etc.)- Exports available in GeoTIFF, JPG, Raw Elevation Values (DEM), Contour DXF (AutoCAD), Contour SHP (Shape File)

3D Model- Exported as an OBJ file, we can deliver a full 3D model of the field and what it looks like with trees, structures, etc.

Point Cloud- We can export .las and .xyz point clouds.

Exports without Plants, Vegetation, Strutures, etc.- These exports provide us with a true portrayal actual ground level elevations and studies. We can have shrubs, trees, tall grass, buildings and anything else in the way removed to put together an true ground level survey.

 

Practical Application:

I met the surveyor team in the field to conduct our surveys together. We capture 8 or more GCP’s (Ground Control Points) that are visible and reviewable in the image to ensure proper scale, elevation, and geo referencing for the exported products. Using these ground control points, we were able to overlay the 2D Orthomosaic JPG image into the CAD program correlating it with the hundreds of GCP’s they are gathering. We were able to obtain roughly a 5cm level of accuracy in the overlay. The advantage here is the ability to providing a true overhead image with high quality resolution for review.

In our conversation and meeting with the Architect on the project, he found many uses and applications for the 3D model, point cloud and elevation models. Using the CAD program called Rhino, we were able to find the following practical uses:

  • We were able to conduct energy efficiency studies based on tree heights and shadow lines throughout different times of the year and day. This helps with deciding where buildings should be positioned and what trees should be kept on the property.
  • The point cloud was used to create a web of points, giving us a true depiction of every contour and change in elevation throughout the property. This NERB was helpful in learning every detail and the land has to offer.
  • The models provided without vegetation, shrubs, trees or structures provided a more optimized NERB layout for the architect to be able to work with to understand the contours of the property.
  • The 3D model provided a layout of the land in an interactive format. The architect was able to plug the house plan models into different areas to see what proposed build sites could look like for visual appeal. Architects are always looking for new ways to present and look at how something will actually appear in the field upon completion.

 

What We Learned and Can Improve On

While this was able to provide a lot of useful information and data to both the Surveyor and the Architect, we had some ways we needed to improve, and here is what and how:

  • The trees in the 3D models looking like Willows and didn’t have really any depth underneath. We can improve this by capturing multiple different oblique images at different elevations of the tree lines to capture a more accurate depiction of what it actually looks like.
  • Being able to provide a 3D model with a more optimized NERB (Showing more of an average of the contours rather than every single countour that exists) to use in adition to the detailed contour models would be useful as well. We can provide a structureless and treeless more optimized model, but we have not been able to provide a more optimized model with the trees and structures on the model at the same time. The architect, if it is worth the time, could probably optimize one themselves. We are researching ways we might be able to provide this in the future.

 

To learn more about how Aerial Mapping can be a great added value to what you do every day, give us a call at (214) 842-6000 or click here to learn more from our website.

  
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