Cleaning the Elevation Terrain is done by flattening objects on the terrain or by flattening any noise created during the photogrammetry process. The first thing you need to consider when deciding whether to clean your Elevation Terrain, is whether your project requires you to complete a survey, generate cut/fill maps, or calculate the volume of stockpiles.
If you are creating a surface for a survey, you do not need to spend time and effort cleaning objects from the terrain. If you are calculating volumes for stockpiles or generating cut/fill maps, you will need to clean objects from your piles, clean noisy water surfaces, or flatten large objects from being in the way of getting an accurate measurement.
Overview
When to Clean the Terrain
Anytime a calculation is required on an Elevation Terrain, you need to look at the terrain as your input for that calculation. And for any calculation to be correct, the inputs must be correct, therefore, you will need to clean your Elevation Terrain to get the most accurate input for any calculation. For example, when the drone was flown and captured the image of the site there was a conveyor on top of a stockpile. You will need to clean it (remove the conveyor) from the stockpile by flattening it so that it isn't included in the calculation.
To clean your Elevation Terrain, you can use both the Remove Object and Replace Terrain tools in the Virtual Surveyor app to quickly remove objects from the terrain. How to decide which tool to use for what object depends on what kind of object it is. For instance, larger objects (such as a bridge over water) may require you to use the Modify Terrain tool in order to properly remove it for a clean terrain.
Situations where you may need to clean the Elevation Terrain:
- To create calculation for Stockpile Volumes.
- To generate Cut/Fill Maps for earthworks projects.
- To remove noise from a Digital Elevation Model (DEM)
- E.g., you may need to remove noise from a body of water or remove terrain distortion from light reflecting off of a roof or window.
When Not to Clean the Terrain
When doing any kind of survey or topography work, you do not want or need to clean the Elevation Terrain. It might help to look at the Elevation Terrain as a literal environment that you need to perform your survey on. You can focus on how to digitally accomplish what you normally would if you were surveying a site in person. You wouldn't flatten trees, houses, or other objects in real life, and the same applies for the virtual Elevation Terrain.
Your survey should look something like the following example image, where your points are placed around large objects and between vegetation and other obstacles. You will still get a lightweight and highly detailed surface.
Virtual Surveyor includes tools that allow you to work around objects (e.g., vehicles, machinery, site materials, etc.) that are found on the terrain, just like you would if you were walking the site gathering points. Except in the virtual world, you can generate points much faster. So instead of cleaning up terrain objects with the Remove Object or Replace Terrain tools, you have access to a variety of tools that allow you to generate points and create a surface while working around any objects or obstacles on the terrain.
Using the Point Grid tool to quickly generate points over a surface may include points that are placed on top of objects. And you can quickly remove any erroneously created points from objects on the terrain using the Erase tool.