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This Process steps through the tasks to create a Civil 3D surface from a subset of Survey Points and Figures in a Survey Database. If you use the Survey Database in Civil 3D, and are working with a large dataset, you can leverage Survey Queries to create surfaces. Surfaces created from Survey Queries do not require that the Survey Points and Figures reside in the drawing file, which keeps drawing file sizes to a minimum and more efficient. Using a Survey Query you can define a selection set of Points and/or Figures using survey properties, like description, name, and elevation. NOTES: Survey Queries are saved in the Survey Database and can be used with any Civil 3D drawing file to create a surface.
REFERENCES: To help you understand these concepts better, view the how-to videos on: Working with Large Survey Databases
When working with large LandXML files there are a couple Import Settings that you can use to limit the size of your drawing files. Upon importing the LandXML file you can import the surface only, rather than importing all of the data that was used to create the surface. In addition to this, you can turn off the Surface Snaphot, which doubles the size of your surface and make your drawing files larger.
NOTES: Removing the surface snapshot will require an indefinite link to be maintained with the LandXML file. If the drawing file size is not an issue, you can keep the surface snapshot.
REFERENCES: To help you understand these concepts better, view the how-to videos on: Import Large Surfaces from LandXML
When working with large datasets, specifically large point files, it is always recommended to create surfaces directly from the point file, rather than first importing the points. Importing a large point files into a drawing is slow and often results in unresponsive and slow drawing files. It is not necessary for the points to live in the drawing file in order to be added into a surface. The best approach to use in this scenario is to first create the surface, then add the Point File to the surface.
To make the surface easier to work with, and keep your drawing file efficient, it is recommended to use a Data Clip boundary to limit the area of interest and/or use lightweight surface styles to limit slow view regeneration times. You will also want to turn on Level of Detail to help improve responsiveness when navigating the drawing.
REFERENCES: To help you understand these concepts better, view the how-to videos on: Create Surface from Large Point File
Point Cloud files contain millions of points, which if added into a drawing file, will bring CAD programs to their knees and make drawing files unworkable. To work with these large data files Civil 3D references Point Clouds externally, and displays them as pixelated graphics. To create a surface from the Point Cloud, you can select the entire point cloud, or a select area of the point cloud. The resulting Point Cloud surfaces are extraordinarily large, and often require an overflow file, which is saved alongside the drawing file and has a MMS extension. Overflow files are needed when the TIN surface exceeds 1.5-2 million points (closer to the latter).
When an overflow file is created, the surfaces and drawings files become very slow and inefficient. You often find yourself waiting for Civil 3D to load data and regenerate the drawing display. This is especially burdensome when Data Referencing the surface into other Civil 3D drawings, causing a ripple effect of inefficiency in all project drawings. To avoid creating these oversized surfaces, it is recommended to keep your TIN surfaces under the point file threshold so the overflow file is not needed. This can be done using a couple different strategies, which include; Simplifying the Surface, Data Tiling, and using Surround & Detailed Surfaces.
This process outlines the basics tasks involved in creating a surface from a Point Cloud, and Simplifying the Surface to avoid creating an overflow file. Keeping surfaces under this threshold will make them much easier to work with.
NOTES: When creating surfaces from Point Clouds it is recommended to use Classified Point Clouds. Classified Point clouds allow you to remove vegetation and other non-ground points to produce a more accurate surface. If using an unclassified Point Cloud you’ll see many erratic spikes through your surface. Civil 3D provides some filtering tools to help address this, but the results are not nearly as effective as working with classified Point Clouds.
REFERENCES: To help you understand these concepts better, view the how-to videos on: Reference Point Clouds in Civil 3D Create Surface from Point Cloud Simplifying Large Surfaces
When working with large datasets in Civil 3D it is important to keep surfaces below the overflow threshold, where an external file must be created. If this scenario occurs, the surface will significantly slow down your drawing files, making them inefficient and unproductive. To keep your project drawing files lean and efficient, it is recommended that you adopt a strategy to avoid creating overflow files. A couple strategies that you can consider include Data Tiling and using Surround and Detailed surfaces. In both cases, surfaces will need to be simplified while still meeting the resolution requirements necessary for your projects.
This process outlines the key tasks that you can reference to Data Tile oversized surfaces into smaller, more workable surfaces.
NOTES: If neither of these options suit your needs, you can consider using Surround and Detailed surfaces, which follows a very similar strategy.
REFERENCES: To help you understand these concepts better, view the how-to videos on: Data Tiling Large Datasets
Another strategy that can you consider when working with Large Datasets is to use Surround and Detailed surfaces to meet your project needs. This concept involves creating multiple surfaces. One surface will have a larger footprint, but will be simplified with much less resolution. The other surface(s) will be smaller, and more central to key area(s) of the project, with less simplification and much higher resolution.
The purpose for the Surround surface is to provide an overall terrain model for the project, with enough accuracy for certain project tasks, like performing a watershed analysis, and to serve as the surround for the smaller detailed surfaces. The Surround surface will cover a much larger area of the site, if not the entire site, and will be heavily simplified to keep the surface under the overflow threshold.
Detailed surfaces will be much smaller areas/regions of your project where more accurate models are needed, for example, earthwork calculations. This could consist of one or more detailed surfaces for your project. The detailed surfaces will be far less simplified, if at all, and kept under the surface threshold of 2million points.
Surround_and_Detaile_001
REFERENCES: To help you understand these concepts better, view the how-to videos on: Surround and Detailed Surfaces
Digital Elevation Models, or DEM files, are used to store and transfer large-scale topographic relief information for use in GIS, earth sciences, resource management, land planning, surveying, and engineering projects. DEM files typically contain land XYZ information at a regular grid-spaced interval to represent ground relief.
DEM files are a valuable data source for many planning and engineering tasks that might not need the type of precision gained by doing a ground or aerial survey. DEM files can also, in some places, completely eliminate the need for specific surveys. Usually, the DEM data is not precise enough to use on small-scale studies, but is ideal for large-scale planning and analysis tasks.
Some examples of projects that can benefit from DEM information include hydrologic studies, corridor planning for highways and pipelines, land use planning and analysis, slope analysis, and large-scale project visualization.
Large TIN surfaces, such as those built from DEM files, can require a substantial amount of memory (RAM and virtual memory) and disk space to build and save the surface. TIN surfaces require about 100 bytes per point, whereas grid surfaces require about 16 bytes per point. As a general rule, a 1 MB DEM file contains 160,000 points. For larger DEM files, the number of points grows proportionately to the DEM file size at a rate of approximately 160,000 points per 1 MB of DEM file size.
Civil 3D uses Grid Surfaces, rather than TIN surfaces, when creating a surface from a DEM file. Grid surfaces are faster and more efficient than TIN surfaces, but have a smaller point threshold. Grid surface exceeding 1millon points will require an overflow file (*.GRS file), which in some circumstances, may be OK for your project work. If the Grid surface needs to be shared and/or used with other project drawings it is recommended to keep these surfaces under the overflow threshold.
This process outlines the tasks for creating surfaces from DEM files, and simplifying DEM files to keep them under the overflow threshold.
REFERENCES: To help you understand these concepts better, view the how-to videos on: Working with Large DEMs
When working with large corridor models in Civil 3D, it is recommended to keep them under 15km/9.3mi. Exceeding this threshold will make drawing files slow, unresponsive, and very inefficient to work in. A strategy that you can use in this circumstance is to partition your large corridor projects into smaller corridors. Along with this you’ll need to adopt strategies for working with large surfaces, like Data Tiling surfaces along your corridor model.
This process covers a basic strategy that you can use to Partition your corridor model into multiple corridors so you can keep your drawings and work environment as efficient as possible. Partitioned corridors function like any other Civil 3D corridor, only special consideration needs to be given to the division of the corridor and target mapping. To optimize your large corridor models there are some techniques you can use to reduce processing and lag times that burden corridor drawings.
NOTES: To partition the corridors you’ll need to determine where best to subdivide corridor model, while staying under the 15km/9mi. If the partitioned corridor model spans multiple surfaces, you’ll need to split regions and change surface targets. In this scenario, make sure the adjacent surface tiles overlap to allow for daylight targeting.
Partitioning_Large_C_001
REFERENCES: To help you understand these concepts better, view the how-to videos on: Working with Large Corridors
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