Tag: DSM

This week I mainly worked on resolving issues in my photogrammetry models and making sure that they are the most presentable that they can be. One issue with the first draft of my models is that the mosaic editor was only displaying DSM (density surface models) instead of DTM (density terrain models). DTM is more applicable for tracking flood levels because it excludes the height of infrastructure that could give false interpretations of the elevation of terrain. I resolved this issue by resetting the step 3 density point cloud features and reloading the final step of the project processing for all five of my key campus locations (East/West Quad, Stine Lake, creek, Quarry Pond).

Another problem I found was that the mosaic editor of Pix4D did not always give accurate readings of the land – terrain levels are shown with a color scale that ranges from red (highest elevation) to purple (lowest elevation). However, tall buildings were still showing up on my models as indicated by their red color. I noticed that in places such as Stine Lake, man-made features like concrete sidewalks were perceived to be the same height as raised land elevations when they were actually much lower. Also, the creek by North Washington Street behind the Office of Multicultural Engagement building was shown on the DTM color map as being the same elevation as the land around it when it is actually slightly lower. Aside from that, even though I was using the DTM feature, some buildings were still interpreted and read as being part of the terrain. I made an inference that this may have been partially due to the fact that the drone did not get extremely low-angled photographs of different land masses from a close enough point of view. I tried to resolve the issue by taking manual photographs of certain areas with the drone where the DTM was not accurate on the map viewer as well as taking more low height photos in a circular movement around structures such the East Quad. Although the low-angled perimeter photos helped me receive more accurate DTM readings, some of my manual photographs were not processed by Pix4D because the angles and height of the photos varied too much. I was a bit flustered by this but I realize that it is all part of the learning experience. Despite the setbacks I am experiencing, I am still advancing in my project at my own pace. I wonder if there is any way the Pix4D mapper pro app would allow me to fly below 99ft if I was in a completely open area that may be detected by GPS? That may improve the quality of my photos for future models.

During the second half of my week I worked on making my models look more visually appealing. There was a lot of extra terrain that was a part of the rayCloud 3D mesh that I did not want to focus on. I managed to figure out how to use the rayCloud editor to trim, crop, and delete data visuals that I thought diverged from the focus areas of my project. I utilized Pix4D features and tools such as drawing polylines and grouping pixels of the model into different categories and reprocessing the 3D mesh so that the triangle meshes of the model would match up with the point cloud editor version of the projects. I also familiarized myself with SketchFab, a 3D model software that allows me to share my Pix4D models by embedding the html code into various websites. Take a look at some of my models below!

I created copies of each of my five models with isolated terrain.  However, when I edited the buildings and other land features like trees from my models, their absence left gaping voids one each model where the infrastructure use to be. The next steps for my project are to find a way to fill in the voids with preexisting land that is in line with the current terrain level. I also need to learn how to export my terrain models from Pix4D to the Carvey 3D Carver so that I can begin creating my wooden models before the Hamilton conference in two weeks. Aside from that, I must recreate my Quarry Pond model so that is is portrayed as a single model as opposed to two separate, floating land masses as it is currently shown to be in my first draft. My current Quarry model looks like a movie set from Avatar which is not what I want at all!

I had originally planned on starting to use the total station this week but only now do I realize that I will only be able to incorporate the total station at the very end of my project once I finished my wooden, physical models due to time constraints. I also have come to realize that learning how to properly use the drone and its features along with Pix4D had taken me longer than I had anticipated. However, I am still fairly on track with my initial project timeline.

I’ve made wonderful progress in my project but there is still plenty left to accomplish! I feel a bit nervous knowing that I have essentially two weeks left to reach my goals but I am determined to do so nonetheless!

 

 

First drafts of models before trimming and merging:

East Quad