What is Cetopo’s ‘Multi-Accuracy’ tool?
In short, Cetopo’s multi-accuracy tool allows users to specify two tolerance levels in one model; an inner area with a higher tolerance (e.g. 0.05m) and an outer area with a lower tolerance (e.g. 0.8m). This means that the terrain in the inner area is accurate to 5cm, while the outer area is accurate to 80cm.
How does Cetopo handle accuracies?
Cetopo’s intelligent algorithm creates a terrain mesh using just enough points to ensure that it is accurate to the specified tolerance, which means more points in steeply sloping areas, and fewer in flat areas. Max Cedercrutz, Cetopo’s founder and CTO explains this below:
“Flat areas require fewer data-points to be accurately mapped. As an extreme example, a perfectly flat plot would not require any data-points in the interior. Cetopo allows the user to specify a tolerance, and then Cetopo will optimize the terrain accordingly (within that tolerance). The way we do this takes into account the specific nature of terrain models, which means that no unnecessary “averaging” is going on, thus preserving as much of the data with as few points as possible.
The tolerance, for example 20cm, means that you can be confident that each point in the model is within 20cm of the original data. Thus for complex terrains, the model detail will not reduce by much, while for flat terrains, most of the data-points are removed.”
What does a Multi-Accuracy model look like?
Initially the appearance of a multi-accuracy model will not differ much from a standard model, but will likely run faster on your computer. The difference can be clearly seen if you edit the terrain. In the example below (taken from Revit model) you can see that there are far more points in the central area, and within that even more in the areas that slope more steeply.
When and/or why would I use this feature?
This feature is particularly popular with Urban Planners, who need to work with large areas of land, but don’t necessarily need to see every ditch and lump, and with Architects who want to understand the context around their site, but only need precise detail around their exact site.
Basically, this tool helps you to run large (in area) site models on almost any computer, without compromising on accuracy around your specific building.
How do I use this feature?
Multi-accuracy models are easy to produce in Cetopo, by following the simple steps outlined below:
STEP ONE: Select an area in Cetopo using the selection marquee tools on the left hand side of the screen.
STEP TWO: Holding ‘alt’ select another area inside your original selection, to create a hole.
STEP THREE: Select ‘dynamic’ instead of ‘holes’ in the left hand panel.
STEP FOUR: Inside your template, specify the inner and outer tolerances under the Terrain tab
STEP FIVE: Download and use!