Translate a Digital Map With GeMS, Part C1

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Translate a Digital Map With GeMS, Part C1 - How to load map unit polygons, lines, and cross section data from another schema to GeMS.

The Geologic Map Schema (GeMS) defines a standard database schema — a database design — for digital publication of geologic maps. This tutorial is one of six originally presented as part of a short course at the 2021 Northeastern Section Meeting of the Geological Society of America by Ralph Haugerud, USGS, on how to use ArcMap and custom tools to create GeMS-compliant ArcGIS file geodatabases.

GeMS Trainings

  1. Getting Started With GeMS, Part A
  2. Digitizing an Analog Map With GeMS, Part B1
  3. Digitizing an Analog Map With GeMS, Part B2
  4. Digitizing an Analog Map With GeMS, Part B3
  5. Translating a Digital Map With GeMS, Part C1
  6. Translating a Digital Map With GeMS, Part C2


Date Taken:

Length: 00:28:16

Location Taken: US

Video Credits

Video editing, Evan Thoms, USGS, Geologist,

Caption editing, Megan James, South Carolina DNR Geological Survey, Geologist,


Our second exercise is to translate an existing digital map, and the process starts out similarly to that of a digitizing analogue map. We need to make a plan. We're then going to transfer features and translate attributes. Stop and talk about it. Move on to non-spatial tables. Chris Halstead sent me, planning for this course, a geodatabase that's a sample, a grab, from their corporate database of the data for a single seven and a half minute quadrangle in southwestern Maine. And this is what he sent me, and again it's a database lots of feature classes and some tables. It corresponds to a published map, Lisbon Falls South quadrangle. Over here, Southwest Maine. The map, well, you can't see it at this scale, so let's zoom in. It's got obviously a map, lots of structural data and, and outcrop information. It's got a title block. author, who did the cryptography, who the state geologist was, publication date. It's got an explanation of map units. Looks very familiar. It's got headings and subheadings. Unit descriptions, some of which are subsidiary to other descriptions. Brackets to organize it. It's got an explanation of lines. We see that there's an anticline on a cross section only. There's a cross section. This kind of woke me up, a contact of uncertain origin. May be a stratigraphic contact or fault. It's an interesting symbol. And lots, and lots of point symbols. And I would note here that some of these are un-oriented, they're, they're about outcrops. Some of them are about, more about outcrop and photo locations, some are, and many are oriented. And there's a very short geochronology table. Two samples. Two locations. Interpretive cross section. And as well on the map, there's explanatory text references, the geologic time scale, photographs and captions, figures, lots of structural data, straight up plots, and captions, and  marginal notes. With the exception of the marginal notes, most of this other stuff doesn't have a ready home in GeMS, but the explanation of units, explanation of symbols, the geochron table, the cross section, all do. To capture these data in GeMS, we need a geologic map feature data set that is a required element with Map unit Polys, and Contacts and Faults. We also need, as needed elements, Orientation Points and Geochron Points, which are standard gems feature classes. We probably also need an Outcrop Points feature class to capture all the non oriented outcrop data, a photo points feature class for the photo locations. We need a cross section feature data set, with the Map Unit Polys and Contacts and Faults again, standard GeMS features, the anticline access that shows in the cross section needs a Geologic Lines feature class in the cross section that we're going to have to put together ourselves, and we also need standard tables, Data Sources, Description of Map Units, Glossary, and Miscellaneous Map Information. So this is my recipe and I'm going to drag this off to the side and do my best to follow it, but we already have ArcMap open. Want to make sure we go to toolbox and let's look at things. Chris very kindly pointed me at a web map service that the main GS runs that makes images of their published Maps available inside the GIS Geo referenced framework. And this is a very handy thing since they can directly look at the database on top of the map image and better understand what the content, the database is. I'm going to put a little bit of the database in here. Let's add some data we're in that geodatabase and let's add contacts and bedrock units. We'll start with there. And oh the web map services are on top, let's put on the bottom and there we can see things, nicely. We can turn this off and have just the contacts on top of the web map service. So I'm going to create a new database. Open up the toolbox. Create new database. I want to put it in, no, that's not where I want to put it. Database is going to be. This would fall South here. I'm going to copy the spatial reference information from what's in the composition already. And that's the web map services, the web mercator. I don't want that. I want the UTM zone 19 used by the main survey for their database. And we have some optional things we want to add. We need a cartographic lines. We need a Miscellaneous Map Information. We need orientation points. And we want one cross section. We don't want edit tracking. We don't want this. We do want LTYPE and PTTYPE. We want standard confidence values. And proceed. It's done. We now go, the catalog window. To load data into this newly made database and, here we have it. Geologic map. Let's look at the bedrock units layer before we begin here. Oh sorry, feature class. It has, in it, edit tracking information that we don't need. Information about patterns that are drawn on top of the polygons, colors of the polygons. The map unit, under unit. And that looks like useful information in there. We want to load unit into map unit. We want to load symbology into symbol and we're going to ignore the symbology overlay for the moment. So let's right click on map unit polys, load, load data. Next, go look for our data set. We're going to go for bedrock units open, add, next, next, and map unit wants to have unit put in it and symbology wants to have symbol and that is it. It looks like everything is there. Let's load the new feature class into Arc. And open up the attribute table and we have map unit and we have symbol and a bunch of other attributes. Looking at the map, none of these map unit polygons are queried, so identity conference for everything is certain. Everything is come from the same data source, the main database we're going to call that data source one. And, I don't think we need to do anything else here right now. We can proceed to load contacts and faults. Let's look at those first. Now here, again, all the edit tracking, we don't need. Comments. The information here, I see, is in two fields: symbology, which has values of contact dashed, contact dotted, contact regular, and non-plotting, and in the draw field, which is either yes, or no. So let's see. I think we want to capture symbology and we're going to stop there. Oh the quad name. It's interesting here that some of these quads, things fall in Lisbon Falls South Quad, and some are shared edge. Suggesting maybe they're map boundaries. So let's load stuff into contacts and faults. Sorry. Next, next. We're going to load symbology into L type. Because we're going to use then that value to figure out what the GeMS attributes of type and confidence and so on are. And we're not going to put anything in there. And I'm going to put draw in the notes field just for yucks. And i'm going to leave type empty. Next, next, next. We should be able to add the contacts and faults here. And open the attribute table and see the type. These are all empty, but we have L type that's populated and the notes field has the, the draw stuff. We can say right now that all of this, again, is coming from data source one. Let's do that. An I think we'll stop with that. Let's see, what's my recipe say I do next. OK, I want to go to the, the non-plotting lines in contacts and faults to find out what they are. And again, back here to the contacts and faults. I'm sorry, wrong, wrong button. Open the attribute table. And we want to go to contact, sort descending. Here are the non-plotting lines, the ones that aren't contacts. And let's look at those, and I want to zoom to selected features and sure enough, they're the map boundary. And this line down the middle of the map which intrigues me. So let's turn off map unit polys, and turn off contacts and faults, turn off bedrock contacts, and this is that funny dash 2 dots Dash 2 dots line, may be a contact, may be a fault. So I'm going to go back to contacts and faults, and find just those two lines. I want no, come on. I need to be editing to do this. Click that one. And I want to zoom. See how much I got? There's a little bit of that same line out here that I haven't gotten. And that's going to disappear 'cause I'm zoomed in too far. Let's shift and click that also and if I bring the attribute table back, we can see that it's these two lines here. And I'm going to say that they aren't simply non-plotting lines, they're not the same as the others and, I'm going to call them fault question mark. And that better be inside double quotes or it won't work. And with these values from the main database, somewhat modified. I can now go to a GeMS toolbox script that uses the LType value to drive setting of all these others. So into the GeMS toolbox and I want to go to attribute by key values. And it might be worth looking at what this does. It steps through a few of the feature classes in the Geologic Map feature database, feature data set and for the independent field LType calculates multiple dependent fields. For us, it's going to be type, location confidence meters, existence confidence, etc. And we need to give it a database. Which is the one we're working on. And it needs a key value file. And here's a brief description of this. It's a text file that describes the mapping from the independent attribute to the dependent attributes, and there is a one of these In the, in the GeMS toolkit. In the resources folder there's an example of this file. And it's designed to rework things in contacts and faults, and orientation points, and it's got a fairly limited number of things it remaps. I have copied this file to my local working directory and renamed it, and added stuff to it, I modified it and so I've got the values that came out of the main database and the one that I invented that say that if LType is a fault question mark, then its type is a fault, it's location confidence meters is 50, its existence confidence is certain, its identity confidence is questionable, and it's not concealed. Similarly, but just simply non-plotting, it's a neat line. We know exactly where it is because it was calculated by somebody and we know what it is and we're certain, we're certain that it's there. We can take this file. We better save it because I made some changes. And pick it out. And run the script. And it tells us what it's doing. And it's not finding anything in orientation points 'cause it's empty, And it's done. We can open contacts and faults and look. LCM is populated, existence confidence and type is populated. We don't need this anymore. We're now ready to load data into the cross section feature classes. Let's start by adding the cross section data from the source database to the map composition. And we want lines and we want units. And. Let's zoom to layer and see where they are. Looks good. If we look at the lines, pretty much, all the information appears to be in the symbology field, and that's basically the line type. So we can open, cross section and go to there, load, load data. Next, select the input data. We don't want to put that there. We don't want that. We do want to put symbology into line type. We should be able to take this now and put it in our map composition. Then turn these off and find we have the same lines in our new cross section A contacts and faults feature class. Some of these lines don't belong in this feature class. In particular, let's open the attribute table and look for, sort ascending, got an anticline axis, which does not participate in the map unit topology, that should be in a different feature class. And we need to select this by, from cross section A contacts and faults. Line type equals get unique values. Mine is selected, we should be able now to export this. Selected features. And let's make sure we're in the same right place. Take 3, Lisbon Falls South, cross section A. Lines. Yes. If we turn off contacts and faults and look at geologic line it's in there, good. We can go back to contacts and faults. And go to the selected feature, let's see. Edit this, start editing. And delete it. Now a geologic lines feature class with one line in it. We also have these lines in here that are the elevation ticks on the cross section, which are a kind of line that does not participate in topology either, and they really ought to be in a cartographic lines feature class in the cross section. So I'm selecting them. And I want to label them something different so I can. Not contact regular, but maybe, elevation tic. Okay, save edits, stop editing. Select by attributes, and we want to select, we want to clear this one. We've selected these, we want to export those. Data, export data. And again, I'm. Be there, there if we turn off the geologic lines. We still see them here. We can go back now to the contacts and faults feature class and the attribute table. And, we have these selected and delete them. The rest of the lines are still there. But if we turn off the cartographic lines, good they're gone. One could argue that these extensions to the side box are also cartographic lines, but they're the same kind of line as this here, which is neat line and participates in the map unit polygons and contacts and faults topology. So I'm going to leave that in there. We've got some cleanup to do. Let's go into here now and let's see, we have a funny gray line that's thin. That is, as I suspect, the ground surface, so let's call that ground surface for the type, not concealed, and we know where it is within a few feet. This map has a 10 foot contour interval. USGS standard is that on a topo map you should be able to read elevations within 1/3 of a contour interval, which would be 3 and a third feet. That's about a meter. That's our location confidence meters. I'm going to clear this selection. Every line on here is not concealed. So we can say. Most of these lines, with the exception of the one I just labeled, we don't really know how well located they are. We know where they are at the ground surface where they intersect the map line, but up in the air, down on the ground, don't know. The symbolization on the source map clearly is not an attempt to say how well located they are. Instead the lines in the air literally are dashed lines below ground are continuous. So I'm going to say we don't know what the location confidence meter is, meters here is. And for numeric fields a good null value is minus 9 or minus 999. We know where every one of these. That it exists. And we're pretty sure the identity of nearly every line on here with one exception. So let's do this and then go to the exception. This is our line and two dots. This is the line that may be, lines that may be faults, or may be contacts and so those Well, we can do it this way here. Those are questionable. And those have an LType. We're using the convention here that they're, on the main part of the map we call them faults questionable. And everything on this map is from data source number one, on this cross section. What else can we say here? We need some symbols. And on here, we need dashed lines. I happen to know in my head what the symbol for a dashed contact is in the FGDC symbol set. Simply implemented by the GSC. And these, are continuous lines. The ground surface we, I don't know what the surface, what the symbol is, I'm going to call it this for now. These lines, some are dash, some are not that's the below ground one it's solid. I believe that is 02.01.02. And I think, edit, save edits. Let's see if we got this right. Let's go to properties, symbology, categories, match to symbols in a style, use the symbol field, match to the FGDC GSC. And, that looks pretty good. That's what we wanted to get. And if we add, cartographic lines and geologic lines, we're in good shape. We also have the cross section polys to add. And, let's look at the source material. We have the unit with symbology. So let's go back to Cross Section A, map unit polys, load, load data, Next, input data is cross section units, open. Next, next. Symbol gets symbology and map unit gets unit. That's done. We should, sorry forgot to add that to the composition. Remove. We can open this, go to symbology, categories, match to symbols in a style, use the symbol field. Let's match to the main GS, and it works. At least we get answers. And it looks about right. Got a few things to clean up in here. Fill in. No queries in here. Everything appears to be certain as to what its identity is. Everything came from data source number one. And, I think, that's it, so we've loaded the feature classes in the geologic map and the cross section feature datasets with the exception of our point data, and we're going to stop right here.