Convert2geo - Model_3 tutorial

This tutorial presents a method how to pre-process a data in the ArcGIS for the software Convert2geo, concretely its Model_3. First point of the modelling is to specify and localize the area that will be modelled. So you need some background materials such as ortofoto images, geology feature or contour lines, which give you enough information about the area. Effective and cheap way how to get these materials is using WMS (Web Map Service). There is lot of WMS on the internet which are free and public accessible, but disadvantage of this method is that user is not allowed to edit the features. Anyway, the WMS is enough source of background information for purposes of this tutorial. The first part of tutorial engages with import of the WMS layers in the ArcGIS, so if you are already familiar with this theme, you could move on the second part of this tutorial.

Import of the WMS layers

There are some map layers, published by “National Geoportal INSPIRE” (http://geoportal.gov.cz/web/guest/home) in this tutorial. Import the WMS server can be conducted by the ArcCatalog, where you open GIS Servers folder and choose “Add ArcGIS Server”. Consequently a new dialog box should occur (Fig.1), where you have to fill a Server URL in. In the case of the geoportal INSPIRE is the right URL (http://geoportal.gov.cz/arcgis/services). Afterwards you just confirm by OK button. If a connection with server was successful, a new item “arcgis on geoportal.gov.cz” should appear in the GIS Servers folder.

Fig. 1: ArcGIS Server Connection dialog box.

Now you can add a WMS feature by the Add data dialog box on the display of the ArcGIS. In the dialog box you need to choose a folder GIS Servers\arcgis on geoportal.gov.cz\, where a wide choice of layers should appear (Fig. 2). An Overview list of the accessible layers and what each layer contains is described on the web page (http://geoportal.gov.cz/web/guest/wms).

Fig. 2: Add data dialog.

In this case you will need these layers:

• CENIA_cenia_rt_ortofotomapa_aktualni – an ortofoto map

• CENIA_cenia_geolog_geomorf – both a geology and geomorphology map

• CENIA_cenia_rt_automapy – a carmap (might be usefull for quick find and movement to desire area)

Pre-processing data by the ArcGIS

The first step I have done was that I chose a area which will be modelled. I chose the area on the base of geology map around Chrastava town (Fig. 3). This area should be enough for demonstration all the capabilities of the Convert2geo. Anyway this area is more or less random, I had no other reasons why I chose this area.

The main intent of this tutorial is to show the process that leads to get a input data for the Convert2geo. Let’s start with that now.

Creation lines of the geology boundaries, cracks and water flows

Firstly you have to create a line shapefile that you can call “SketchUpLines”. Coordinate system of this shapefile can stay unknown for this case. Secondly you open attribute table of the SketchUpLines layer and add new one field called for example “Feature”. You have to set the type of the field like “text”. Subsequently you can start to sketch the lines by tool (Editor). You should begin with creating outside boundary of the all area (Fig. 6). Very important is a proper setting of the snapping and to take sure that the line is closed, in other words that last vertex of line is also first vertex.

Fig. 6: Outside boundary created by Editing tool.

The attribute Feature of this line you have to fill in by a note “1_1”. Meaning of this note is explained in the table (Tab. 1).

Fig. 7: Example of the attribute (Feature).

Afterwards you can continue with sketching all the left lines such as inside boundaries, cracks and flows (Fig. 8). Again you should help yourself by proper setting of snapping and should fill the Feature attribute in by a proper notes.

Fig. 8: One of the inside boundaries.

On the image below you can see all the lines that was done by the sketching in the Editing tool.

Fig.9: All lines.

Spliting lines at vertices

In this step you are going to use ArcGIS Toolbox Tool (Split line at vertices) that gives you lines which better describe the specific features. Thanks to this tool you are getting the new one shapefile named for example “SketchupLines_SplitLine” where is each line splitted on the smaller lines. You can see a change in the attribute table where is significantly more items (Fig. 10). As well you can see that the values of the attribute Feature stay preserved in accordance with the previous lines.

Fig. 10: Splitted lines and their relevant values in the attribute Feature.

Identifying of the elementary cycles in the graph

In this case you are going to identify the base cycles by feature groups. Firstly you use the tool (Feature To Polygon). Output of this tool is polygon shapefile you can name for example “Groups”, where every polygon represents one base cycle. Secondly you have to add new field “Group” and fill in that with values in the range from 1 to amount of polygons (Fig. 11).

Fig. 11: Polygon layer representing a groups (cycles in the graph)

Intersection of the line and polygon layer

The Information about what line belongs to which cycle you can get thanks to tool (Intersect). The input layers are the SketchupLines_SplitLine and the Groups, the output layer you can name for example “Lines”. Afterwards you should join both attributes Group and Feature together. The form of the join is as follows (“Group_Feature” for example “1_1_1”) and the result values you can save to new one attribute named “Feature_all” (Fig. 12). Further explanation is in the table (Tab. 2).

Fig. 12: Post-Intersect table with fields joined together.

Creation points from splitted lines

In this case you can use the tool (Feature Vertices To Points). This tool creates new point layer and gives you start and end point of each splitted line. You can set the name of output layer like “Points” and in the dialog box of the tool is very important to choose item “ALL” for Point Type parameter. Every value in the attribute “ORIG_FID” should be doubled, like you can see on the image (Fig. 13).

Fig. 13: Vertex points.

Summarize the point layer

You can release the tool “Summarize” in the table of layer Points where you have to right click on the head of attribute ORIG_FID. In the summarize you have to choose FID.First and FID.Last statistics to be included in the output table. Unfortunately we are not able to include key attribute FID in Summarize, therefore you have to copy all values from FID to any attribute for example “ID” and to use this attribute tool instead of FID (Fig. 14).

Fig. 14: Summarize tool.

Result of the Summarize is table where are two attributes that represent identification numbers of points of each line, in this case are these attributes called like Minimum_Id and Maximum_Id.

Fig. 15: Result table of the Summarize tool.

Joining data two tables ("Lines" table and summarized table)

In this point you will move the data of the both Minimum_Id and Maximum_Id attributes into table of layer "Lines". Firstly you should create two new fields in the table of layer "Lines". The new fields can name “1” and “2” and the type should be “integer”. Secondly you can join tables of layer Lines and Sum. The join is going to be into layer Lines where you choose the field FID_Sketch like base attribute of the join and the table Sum where you choose field ORIG_FID Fig. 16. If the join was success all fields from table Sum should appear in the table Lines. Next step is to copy data from field Minimum_Id to field 1 and field Maximum_Id to field 2. Once is copying done you can remove that join between Lines and Sum tables. Now you have got a final form of table Lines that is as well input file for the Convert2geo.

Fig. 16: Joining data in the tables.

Adding X, Y, Z coordinates to point feature layer

The Last step is adding X,Y respective X,Y,Z coordinates into table of layer Points. You can use the tool (Add XY Coordinates). Finally you should add new field Z and fill this field in any value you need, that depend mainly on the level of the layer (top, middle, bottom,..).

Fig. 17: Coordinates X, Y, Z.

Required data in the Convert2geo

This chapter only describing what kind of data do you need to open in the Convert2geo. The two schemes of the tables below detailing both a point and a line table. You can need more point tables that input into Convert2geo, depend on the amount of levels you want to create. The point table ordinarily should contain coordinates X,Y, Z, where Z should be different for each table.

Tab. 1: Scheme of point input data for Convert2geo.

Line data table is always only one for all levels, in other worlds we use the same line data for every layer.

Tab. 2: Scheme of line input data for Convert2geo.