ArcGIS - Geodatabase Topology - Part 1

today's lessons gonna be an exciting way we're to look at how to create topology within a geo database so this follows with the lessons of how to create and edit within a geo database and often the next step is to establish topological rules between different feature classes and within a feature class we're going to learn the kind of the basics on how to do that so right now I've got a geo database set up the key to doing topology is that I have to have not only the geo database but in another container called a featured data set the feature data set is makes all the peach classes within it has to be the same coordinate system and the same underlying resolution or tolerances and those are key to the topology tools working correctly so within the feature data set I've got a series of different feature classes these are all for Yellowstone National Park so if I kind of quickly look to these I've got the boundary file kind Ranger districts roads and trails now just at first glance all this looks pretty good and probably I assumed in it would look cartographically pretty good but for doing analysis that's a network analysis with trails or looking for small little mistakes in this data topology rules are really important for finding those errors and correcting them so they're key to having quality control and integrity with your data both for analysis and other types of work so we're gonna go back here and you can go inside that future data set and either here on the feature data set or here in the content pane go to new and create a new topology this is gonna launch a little wizard this can allow us to make all the settings for a topology so let's assume you're gonna read all the details and go to the help files if you need it well let's go through this and see what it's asking for so it's gonna ask us for a name I'm relieved that from a default asking for a cluster tolerance this is where it's going to use this cluster tolerance to decide when two points that are really close are exactly the same this is defaulting to the XY tolerance of the featured data set and general those should be the same here we're pretty small and it's just one one millimeter so I'm going to go up to one centimeter and so that's gonna define kind of spatial resolution of my vector data here anything within ten centimeters is going to be snapped together then I need to let the tool know which feature classes are going to participate in topology feature classes can only participate in one topology so if I selected here I can't create a second topology and include the same layer so for right now we're gonna look at just trails and the boundary next it's going to ask me to rank these two so if it needs to move something it's going to move the features in the lower ranked data set more than in the higher-ranked data set so if you have let's say the boundary here I don't want to move it all I consider that to be my kind of master layer and I'm okay if the trails moves a little bit to match the boundary so I want to change the rank of trails to be lower than the rank of boundary and I've got quite a few feature data set of feature classes in my topology I may need to increase the number of ranks now I need to set up my topology rules there's quite a few rules here so you definitely need to look over Ezra's help files I got a nice poster that shows a visual illustration of all the different topology rules for points lines and polygons so that's a must before kind of proceeding to adding these different rules so I'm going to apply a couple of them and this is an extensive list you might want to apply more if this is a real scenario so I'm gonna start and I'm gonna say that my trails I want to make sure that they're inside the park boundary so I'm gonna go to trails and look for an appropriate rule here I think that's been a while since I've looked at these must be inside the future class of boundaries I think that's the right rule we'll find out when we actually look at the the errors in this rule so I'm gonna say okay for that one so that's one rule that's been added I'm gonna create another one that's just for the trails itself so I'm gonna say the trails must not overlap so this is just one feature class that's involved so I can't have a trail that overlaps itself or another trail that shouldn't be allowed so I'm gonna say okay and now I have two different rules for my topology go to next it's a summary of the topology and say finish now it's going to create the topology and it's gonna ask me if I want to validate it and generally you want to say yes but I'm gonna say no here just to show you something and I'm going to then click on the topology and I can preview it I can visualize what its gonna look like and right now I get this hashed blue box over my whole study area and this is showing me the quote dirty areas the area is in my study or my in my feature data set that haven't been validated yet and as you do topology and make edits and make changes and apply new rules you're you may have dirty areas for part of your spatial extent but not the whole thing so in this case right now since I haven't bought anything the whole spatial extent is dirty I can right-click on this topology and do the same thing I can validate it's a new some cranking here in order to find the features that don't match those two rules and then sometimes in this case I'm going to f5 maybe go away and come back and now I see all the places that I've gotten rule violations it looks like I have a lot of trails that go outside the park around the edge and a few interior issues here know what's good at this point before we switch into arcmap is to go to your topology right click and go to properties and then we can look at the errors and generate a summary and this gives us a sense of the number of errors that exist for the topology rules that we've established we've got twelve points this is something that's universal across topology of points that are larger than the cluster tolerance with offset so 77 errors total and now our next step is to deal with them and we're not going to do that inside of arcmap we're sorry our catalog we need to do that arcmap so we'll do that in the next video thanks

Channel: Eric Compas

Views: 15,485

Rating: 4.9365077 out of 5

Keywords: ArcGIS, ESRI, geodatabase, topology

Id: mT2je0Ldsnc

Length: 7min 21sec (441 seconds)

Published: Wed Feb 25 2015