![]() Like with any CAD or BIM application, keeping drawing and modeling close to the file’s internal origin ensures better accuracy and performance. In cases where such a CRS is not readily found, other resources such as EPSG.io can help to find the CRS, or its EPSG code number.Īside from utilizing the right CRS, users find the overarching issue of BIM and CAD file collaboration relates to internal and user origins, which are vital to understand when dealing with project coordinates a large distance from 0,0. ![]() The option for “Well Known Text” is more open to the specific coordinate system site designers may need to choose. Users can enter projection information in the Georeferencing dialog box or, when a projection is picked in the selection pull down menu, the predefined projection codes are automatically entered. CRS Lookup dialog in Vectorworks Landmark Figure 1.1 depicts a CRS name being chosen. In the BIM application Vectorworks, georeferencing enables easy location of each project’s proper coordinate system through a Coordinate Reference System (CRS) lookup. If firms expect to use and trade the file among other collaborators as the standard basemap or background, then using the same PCS will aid in keeping the site designers’ work in line with everyone else’s. Site layout plans typically provide a point of beginning and legal demarcations which relate directly to a known state/regional/country plane, and this becomes the PCS for their file. So, why does knowing the PCS matter to architects, landscape architects, and other site design professionals if they are not trying to use GIS? The meets and bounds, property maps, plot plans, and base map files received from survey and civil engineers are why knowing PCS matters. Fortunately, certain GIS map projections utilize these conventions. This helps to transfer to flat mapping and the conventions of X and Y but of course that leads to some skewing. Those mappings have 3 general options for transforming GCS to a Projected Coordinate System (PCS): Conical, Cylindrical, and Azimuth. This is the Geographic Coordinate System (GCS), which is not applicable to flat mapping. The lines connecting north pole to south pole are longitude lines, while those circumscribing the earth easterly and westerly are latitude lines. For a quick understanding, imagine angles drawn from the center of the earth to the surface. So, we have to consider how to translate/transform real-world locations and imagery to a flat 2D surface.ĮSRI’s Understanding Map Projections explains the convention of latitudes and longitudes. With projects large enough to concern the earth’s surface curvature, though, the challenge is that general coordinate geometry relates only to flat surfaces. We are all accustomed to the positioning system X and Y, also known as Easting and Northing. Many haven’t been required to think about geometry’s coordinate location unless the object involved a property line, ownership boundary, roadway layout, or similar feature that required coordinate layout to meet the legal or buildable description of the entities. ![]() Save this picture! Urban Context Model - Niterói Brazil.
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