Creating a TIN Surface with the DJI Zenmuse L2 and PIX4Dsurvey

We used our L2 point cloud to create a ground surface model in Pix4Dsurvey. First we drop our L2 las files that were exported from DJI Terra into Pix4D and click Start. Survey then has us confirm the coordinate system and the vertical model we are using with our data. In this case, we use GEOID18. We click Apply and the point cloud is imported. Once the point cloud has populated it will open in the Layers tab where we can see everything we will generate. We did not have any points classified so that is our first step.  

We click on the Processes tab and go down the list starting by removing any major outliers in the data. Then we can decide our sample distance, rigidity, and above ground threshold for classifying our terrain. In this case we left the defaults in place. Once we click Filter Terrain, we will see that Survey has accurately identified the Ground Points from non ground points. If we go back to the Layers tab, we can see all the previously unclassified points are now classified. We can also toggle visibility of the different classes of points. If you aren’t happy with the classifications, you can adjust your settings and filter the terrain again.  

The next step is to create our Grid of Points.  We left the defaults in place and Clicked Make Grid. Now we can generate our TIN. With no adjustments to the defaults we have a decent surface model. We also added contour lines and then viewed all the layers we created. In the Exports tab you can determine the file types and destination folder. Click Export. Now your TIN is exported as a landXML file. We have the option of fine-tuning the data as well. In the Settings tab, we can adjust our views, point sizes, and backgrounds. We can also utilize the tools in the top toolbar to correct spots in our data or measure volume and distance.