Extracting data from Geological Map of Canada - Map D1860A

     The Geological Map of Canada is distributed on CD as ARC/INFO coverages and ArcView SHP and SHPGEO files. There are also doc, HTML, and Surview directories.

     The Grenville coverages have been archived in iomega:\GRE (catalog) in the schemas ROXGRE (.ADF files), SYMGRE (Symbols, IMO.TXT, IMP.TXX, *.ADF), RIVGRE (Rivers, ADF), LAKGRE (Lakes, ADF), FLTGRE (Faults, ADF), BNDGRE (Geographic Boundaries, ADF), INFO (arc.nsp, arc.dir, *.NIT - has field name information; and *.DAT - path to information in /gre/*gre/*.ADF files). The catalogue is iomega:\GRE, and in 300lab (GSMCAD) as :\GRE\ROXGRE, etc.

     Each of the primary data directories (\COVERS, \E00, \SHP, and \SHPGEO) contains ten subdirectories: one for each of the eight compilation blocks (by author) and two for all of Canada.
    Each of the ten subdirectories in the \CANADA\COVERS directory contains a complete Arc/Info 7 workspace. All Arc/Info coverages are single precision. It should be possible to access all of the coverages directly from the CD-ROM. There are nine workspaces of geological data (one for each compilation block and one for all of Canada). Topographic bases for all compilation blocks are located in the CANADA\COVERS\BAS subdirectory.

    Two interchange file formats ensure compatibility of the data with a wide range of GIS systems:
    Filename extension Description
    .E00   Arc/Info 'Export' (PC ANSI text)
    .SHP   Arc/Info 'Shape' (binary)

    Each of the \SHP, \SHPGEO, and \E00 subdirectories contains a set of directories and files which correspond to the Arc/Info coverages.
    *.SHP (\CANADA\SHPGEO\...)

    The \CANADA\SHP files contain coordinates for the Lambert Conformal Conic projection. Neither ArcView nor SurView can reproject these files to another projection. Therefore, the entire \CANADA\SHPGEO directory tree contains a duplicate of every file in the \CANADA\SHP directory tree, but containing geographic{geodetic} (longitude, latitude) co-ordinates instead of Lambert. All *.SHP, *.SHX, and *.DBF files in this directory tree have a 'G' suffix to indicate that the file contains geographic (geodetic) coordinates.
    You can use these files instead of the Lambert files if you want to use the Geological Map of Canada as a background for other geophysical, geochemical, or geological data that is only available in a non-Lambert projection.

    Importing ARCVIEW - ARC/INFO files into Autocad Map

     DATABASE Terminology: the environment consists of the database management software (DBMS) such as dBASE, ORACLE and the databases it can access. A catalog refers to the directory path to the database. A schema refers to the catalog subdirectory (folder) where the database tables reside, and a table contains rows (records) and columns (fields, data element) of data that can be linked to map objects via a link path name containing the environment, catalog, schema, table and a key column (e.g. the record number ‘statnum’ in the stati table in the case of Fieldlog).
     In the case of the Geological Map of Canada on the departmental server, the catalog is:
     The folders schemas containing the database tables include the rock data folder ROXGRE, the fault data folder FLTGRE, the river and lake RIVERGRE, LAKGRE folders, respectively, and the SHP/GRE folder, all of which contain .dbf, .shp, .shx. and .asx data files.


    ArcView Shape files

     ArcView point symbols, line styles, colour, and fill styles are not supported in Autocad Map. Polygons in ArcView are represented as closed areas, and appear as closed polylines, rather than a topologically defined set of contiguous arcs.
     Attribute data in ArcView is contained in the .dbf database files and coordinate data in the .shp/.shx shape files.  .asx files contain data concerning specific fields in the .dbf table, e.g. the file  Roxgreer.asx for the Era field in the ROXGRE.dbf file contains the following information:

    title= Geological Map of Canada (GRE) - Era
    title2=Carte géologique du Canada (GRE) - Ère

     Database fields are referred to as 'Data Elements' and the data in the fields are referred to as 'values'. For example the field 'Age' is a Data Element whereas 'Mesozoic' or 'Ordovician' would be a value of the Data Element.


     Importing ArcView images

    In the Import procedure (Map -> Map Tools -> Import) you will first be requested to select the ArcView .shp file, e.g. roxgre.shp, containing the coordinate definition of the geological polygons to be imported. Click the Proceed button to display the 'Import Data Options' dialog box.

    If the 'Map Data Elements to Object Data' option is selected in the 'Import Data Elements' selection box, clicking the Data button calls a 'request box', in which is entered a Table name, e.g. Grenville1, for the Autocad Map Object Data Table to be attached to the Label points ('centroids?') of the ArcView polygons that will be plotted in Autocad Map. Both points and arcs will be located on Layer '0' in Autocad Map, and all the fields, e.g. Age, and all the values (e.g. Mesozoic) in those fields will be contained in the table attached to the plotted label points.
    If it is required to create a map with the data sorted into layers according to the values in one of the data fields, for example, Mesozoic, Paleozoic, and Precambrian values in the ERA field, select Map Data Elements to Layers in the 'Import Graphics' selection box. Click the Layers button and in the scroll-down Control Data Elements box select the Field  e.g. ERA, containing the data values Mesozoic, Paleozoic, Precambrian, and click the Auto Layer button. The layers created will be identified by the value names.
    It is also possible to select one value or some choice of values to import on separate layers, e.g. the Paleozoic value in the Era field. Give a name to a new Target Layer (e.g. Paleozoic) in the Target Layer options box. This will be the layer on which those objects associated with a given field value will be placed. Click one of the values in the Values Available drop down menu, e.g. Paleozoic, and transfer it to the Values Assigned box by clicking the double arrow button. Repeat this procedure to add a second value, for example, make a new Target Layer named 'Mesozoic' (the Values assigned box will become empty) and transfer the Mesozoic value from the Values Available box to the Values Assigned box. Click the OK and Proceed buttons. A '0' and a Paleozoic (and Mesozoic) layer will be created in Autocad Map.
    The '0' layer will contain all the polygon definitions and associated 'centroids?' not included in the Paleozoic (and Mesozoic) layers, whereas the 'Paleozoic' and 'Mesozoic' layers will contain only polygons and 'centroids?' associated with the Paleozoic and Mesozoic rocks. If the 'Paleozoic' layer is made current and the '0' layer is frozen, then only the 'Paleozoic' polygons and 'centroids?' will be displayed. (Note: the Arcview 'centroids?' are not recognized as topological by Autocad, and consequently therefore any topological object data attached to the 'centroids?' will not be useable.)
The Paleozoic polygons can now be coloured with the 'fil'  (ADEFILLPOLYG) function.
     A topology can also be created (use Map -> Drawing Cleanup to remove duplicate lines, etc), with the ArcView label points being used as Autocad centroids.
    If the map is saved as a .dwg file, the data in each of these drawings can be accessed during some other drawing session by attaching the drawing via Map -> Drawing -> Define Drawing set.
     To import a layer from an external .DXF file, attach the file (Map -> Drawings -> Define/Modify Drawing set, etc) and query the layer via Map -> Query -> Define Query -> Property -> Layer -> Values -> select the layer(s) to import. Note that once a layer has been added to the current drawing, it cannot be deleted from layer list.
     Since the map was drawn using the Lambert Conformal Conical Projection the imported data can be translated into some other projection by simply setting the current drawing session to the desired projection with Map -> Map Tools -> Assign Global Coordinate system -> Click to Current Work Session -> click the Codes button and select the Coordinate system in the drop down selection box.
    The Grenville Province .SHP files are archived in Iomega:/GRE/SHP, and E:\GRE\SHP\GRE.

    To reduce the area of the map to be displayed, use the Autocad Boundary Trim. First draw a rectangle around the area to be trimmed. In Map -> Map Tools -> Boundary Trim select this rectangle as the Boundary in the Select Boundary selection box, enter 'automatic' as the Objects to Trim, and 'Trim Outside' as the Trim method Click the Delete button in the 'Objects that cannot be trimmed' selection area, and then the Proceed button.
    TIP: import each value as an individual layer, freeze the value layer and delete the data on the '0' layer. Save as a .dwg file that can later be reattached and colour filled or hatched.


     Coverages in Arc/Info are equivalent to topological layers in Autocad Map (ref, p. 148).
    In \Canada\Covers\GRE\ROXGRE\file.adf,  ...GRE is the workspace, ROXGRE the coverage (or SCHEMA, see above), and each file(.adf) in the coverage contains a specific kind of data, e.g. arc.adf contains coordinates for arcs, tic.adf coordinates for tics, and Aat.adf and Pat.adf are attribute values files. Polygon elements are imported such that each arc of the polygon is converted to a polyline on layer ARCS and each label point is converted to a point on the layer LABELPNTS.
    The polygon record number is keyed on the label point. (Arc/Info universal polygons, tables related to feature attribute tables, text attributes, regions, route systems, address files, turntables, LOG files, fonts, symbols, linetypes, and shades are not supported by Autocad.) When an Arc/Info cover is imported into Autocad Map, it is imported in three components:
     1) arcs delineating polygons;
     2) label points which resemble but which are not centroids;
     3) object data attached to the label points;
    The data may be imported as arcs and label points with or without the attached object data.

     To import the ARC/INFO coverage into Autocad

    In the Import procedure (Map -> Map Tools -> Import) you will first be requested to select the Arc/Info coverage, e.g. \U171\Canmap\Canada\covers\GRE\ROXGRE\. Click the Proceed button to display the 'Import Data Options' dialog box.
    The rest of the import procedure is as for the ArcView files. The main difference is that:
    1) the drawing elements are arcs (links, lines) rather than polygons.
    2) all the arcs are located on the 'arc' layer rather than together with the label points on the '0 layer'.
    3) label points not assigned to a defined layer are contained on a Labelpnts layer.
    4) only the label points are imported to the layers defined in the Import Graphics/ Map Data Elements to Layers procedure.
     (Note: the points can be enlarged and coloured, and therefore made more visible using Format -> Points to change the symbol and size properties of the point symbol, and Change > Properties to change the Colour and ltScale,  followed by REGEN.)
     In Fieldlog it would also be possible to plot only points with e.g. Paleozoic, in an ERA field in a Fieldlog table, and also to place them on their own Paleozoic layer (defined and made current prior to making the Query). Similarly, a layer for 'Mesoproterozoic volcanics' could be defined and made current for the mapping of a Query in Fieldlog for a value = 'Mesoproterozoic' in a field named Ages, and a value = 'volcanic' in a field named Lithologies.


     To examine the Layers use the Layer Editor in Autocad. The lines representing the boundaries of polygonal objects are contained on an ARC layer, the centroids of the objects are stored on the layers corresponding to those objects, whereas the centroids of objects with undefined fields are kept on a layer called labelpnts.  If all the fields are turned on, a centroid will appear within each of all the geologically defined polygons. If only one of the layers is chosen, e.g. the Paleozoic layer, only the centroids of those mapped units whose ERA field contains the string ‘Paleozoic’ will be display. However the object data attached to the centroid, examined via Map -> Object Data  -> Edit Object Data, will include all the fields and values in the imported object data table (not merely the fields selected as layers), and including the area and perimeter of each polygon to which the point acts as a centroid. Autocad does not however recognize the label points as topological centroids from which it is possible to create seperate polygon layers in Map -> Map Tools -> Create Closed Polylines. A separate topology would need to be created after cleaning up the Arc\Info arcs with the Drawing Cleanup procedure. However, you could ‘manual select’ the arc sets to be cleaned, and ‘manual select’ the arcs from which to create a topology, in order to make a polygon layer of only, for example, the areas of Paleozoic rocks. BE CAREFUL WITH THE TOLERANCE SETTING!
     To make a topology such that the points to which is attached the ARC/INFO attribute Table will also be the centroids of the polygon topology being created, define the topology with the arc and attribute data layers turned on. The data point will then automatically be taken by Map as the centroid to which both the polygon topology table and the Arc/Info attribute table will be attached. If the attribute layer is frozen, Map will create a new set of centroids on a separate layer (see c:\aacrse\505\acad\topol\example)
     Different polygon sets can then be displayed in a new drawing via  Map -> Query -> Define Topology Query -> load the topology -> Query Type = Data, expression operator = e.g. granite. (First attach the original drawing!)

    ARCView files for the Churchill Province in H:\CANADA\SHP\CHU
    12/13/96  02:57a                   251 BNDCHU.ASX
    12/13/96  02:57a                 2,778 BNDCHU.DBF
    12/13/96  02:57a                 6,420 BNDCHU.SHP
    12/13/96  02:57a                   164 BNDCHU.SHX
    12/13/96  02:57a                   160 CHU.FDL
    12/13/96  02:57a                   244 FLTCHU.ASX
    12/13/96  02:57a               726,652 FLTCHU.DBF
    12/13/96  02:57a               392,884 FLTCHU.SHP
    12/13/96  02:57a                13,332 FLTCHU.SHX
    12/13/96  02:57a                   307 IMPCHU.ASX
    12/13/96  02:57a                 3,619 IMPCHU.DBF
    12/13/96  02:57a                32,924 IMPCHU.SHP
    12/13/96  02:57a                   156 IMPCHU.SHX
    Lakes and Coast lines
    12/13/96  02:57a                   257 LAKCHU.ASX
    12/13/96  02:57a               197,578 LAKCHU.DBF
    12/13/96  02:57a               421,284 LAKCHU.SHP
    12/13/96  02:57a                 5,924 LAKCHU.SHX
    12/13/96  02:57a                   247 RIVCHU.ASX
    12/13/96  02:57a               511,566 RIVCHU.DBF
    12/13/96  02:57a               600,500 RIVCHU.SHP
    12/13/96  02:57a                13,508 RIVCHU.SHX
    12/13/96  02:57a             4,656,026 ROXCHU.DBF
    12/13/96  02:57a             4,561,604 ROXCHU.SHP
    12/13/96  02:57a                29,844 ROXCHU.SHX
    Thematic maps
    12/13/96  02:57a  era              329 ROXCHUER.ASX
    12/13/96  02:57a  period           340 ROXCHUPE.ASX
    12/13/96  02:57a  rock by era      392 ROXCHURA.ASX
    12/13/96  02:57a  rocktypes        347 ROXCHURC.ASX
    12/13/96  02:57a  rock subdivision 377 ROXCHURS.ASX
    12/13/96  02:57a  units            334 ROXCHUUN.ASX
    12/13/96  02:57a                 4,369 SYMCHU.BOB
    12/13/96  02:57a                12,259 SYMCHU.DBF