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.
When to Clean the Terrain
Any time you require a calculation on the Elevation Terrain, your terrain needs to be viewed as an input for that calculation. For any calculation to be correct, the inputs must be correct, so you will need to clean your Elevation Terrain to get a clean input for any calculation. E.g., there is a conveyor on top of a stockpile when the drone captured the image of the site. You will need to clean it from the stockpile by flattening it so that it isn't in included in the calculation.
To clean your Elevation Terrain, you have both the Remove Object and Replace Terrain tools to help you quickly remove objects from the terrain. Larger objects (such as a bridge over water) may require you to use the Modify Terrain tool in order to properly clean your terrain.
Instances where you may need to clean the Elevation Terrain:
When Not to Clean the Terrain
When doing any kind of survey 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 would normally do 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.) found on the terrain, just like you would if you were walking the site gathering points. Except you can generate points a whole lot faster. So instead of cleaning up terrain objects with the Remove Object or Replace Terrain tools, you have access to a variety of tools to generate points for creating a surface around those objects.
Using the Point Grid tool to quickly generate points over a surface may place points on top of objects, so you can remove some of those created points off of objects on the terrain. This can be done quickly using the Erase tool.