GIS to CAD / CAD to GIS Workflow

in this tutorial we will look at a workflow to bring GIS data into a CAD based program I will also show you two ways to bring CAD based data back into a GIS environment so that the data is properly aligned and projected on a base map first we need to acquire data that we will use in our workflow I have downloaded a data set from the city of Victoria's open data website as you can see the city provides contour data at 1 meter intervals and also building footprints and heights I have downloaded these data sets to demonstrate the GIS 2 CAD workflow here I have started a new session in arcmap through the add data button I can add in my downloaded datasets I am also going to add in a base map to ensure that the data is formatted correctly and properly aligned we can see that the data sits correctly when I right-click on one of the data layers that I have added go to properties and then click on the source tab we can see that the data is projected in an ad 1983 CSRs UTM zone 10 and format this projection is also using a metered measurement system this information is important to know for later on when we bring our data from CAD and back into GIS note that this projection is only useful on the specific geography and data type that I have brought into the scene this nad 1983 UTM zone 10 and location will not correctly display data in other areas of Canada generally good data will name the projection system or geographic coordinate system in a metadata description or readme file that is attached to the data I am now going to export the contour data and building footprints to CAD format I can do this by right-clicking on my dataset and selecting data export to CAD the export to CAD tool lets me add in multiple layers from my table of contents so I will click on the drop-down button and select my buildings file as well for output type I find it is best to use an older CAD format in order to ensure compatibility across multiple CAD programs I have chosen drawing format 2004 the output file path will be the location and name of the drawing file once it has been exported once I have filled in all relevant information I can click OK and my drawing file will be created now I can switch into a CAD based program to view my data for this example I am using Rhino as my preferred CAD based program I am going to open the data that we just exported and we will see that our data displays correctly in the screen the CAD system has even recognized the elevation data values and has translated the data into 3d space I am now able to work with this line work as I normally would with any CAD data set now that I have modified my CAD data I want to bring this data back into a GIS environment that I can perform a GIS analysis and build up a map to do this I'm going to export my data to a basic CAD format such as a drawing file again once this is completed I will start up a new map session in arcmap the first thing I want to do is add in a base map by clicking on the drop-down next to the add data button I will add in a topographic base map so that I can ensure that the data I will be importing is properly aligned on the world map next I will add in the DWG file that I just exported after adding in this data a warning pops up saying that the data source that I have added is missing spatial reference information if I click OK and then right-click on the data and select zoom to layer you can see that the data is showing up on the map but it is floating in the middle of the ocean this is because arcmap has read the data correctly but a projection file is missing this projection file is what tells arcmap where to place the data on the world map I will need to reprojection that I have just added first I will export my CAD data into a shape file to convert the data back into a GIS format you will see that the CAD data has been imported as a group made up of multiple layers or points lines and polygons since I only brought in contour data I only need to export my polylines so I will right click on the file and choose data export to create a shape file of my imported contour lines you next if I click on Windows search and type too projection into the search box I can access a tool that allows me to reassign a projection file to my contour line shape file by clicking on the box next to coordinate system I have the ability to browse or search for coordinate systems as you will remember from earlier in this video the data that we initially downloaded from the city of Victoria was created in nad 1983 CSRs UTM zone 10 n so I will search for UTM to make my search a bit easier once I have found the correct projection system I can click OK we can see that the data is now sitting back in the right place on the map it's possible when working in a CAD system that I will accidentally move my data back to the 0 0 grid origin that most CAD systems use to start a drawing if this is the case I will need to manually align my CAD data back to the correct place on the map you first I will add my data to my map data frame and export the polylines to a shape file you then I will define the projection projection of my data in this case nad83 CSRs UTM zone 10 n you when i zoom into the data you can see that it is not properly aligned with the map I will have to run a spatial adjustment to correct this problem first I need to ensure that my editor toolbar and spatial adjust toolbars are showing if they are not I can right click on my MT toolbar space to enable them next I start an editing session then I will start my spatial adjustment first I need to set the data to be adjusted I will choose to adjust all data in my contour layer next I need to choose the adjustment method I will choose transform similarity if you are interested to learn more about the different transformation methods refer to the help contents in arcmap now I need to create a series of displacement links these are reference points that I will pick that my data will try to align itself to in order to speed up this process I'm going to create two bookmarks so that I can easily switch between views of where my data is currently lying and where it is supposed to be positioned you you generally need at least three displacement points in order to properly align the data you after creating these points click adjust your data should be closely aligned to the map but you may need to run the tool again to improve the data's alignment accuracy you this completes the tutorial on taking data from a GIS environment into a CAD based environment and then bringing the data back into GIS for later analysis in the next tutorial we will perform a flood analysis on the contour data that we have just brought back into arcmap

Channel: Esri Canada Higher Education & Research

Views: 16,522

Rating: 4.830986 out of 5

Keywords: esri canada, CAD, GIS

Id: -aC0_Yt7hCM

Length: 10min 35sec (635 seconds)

Published: Fri Oct 27 2017