Importing Maps into
Petra
Petra
is a product of “geoPLUS Corporation” (918) 971-7071,
www.geoplus.com.
Petra
provides unique, PC-based solutions to data management, manipulation,
visualization, interpretation, and integration of geological, geophysical,
petrophysical and engineering data. Results can be quickly visualized using the
interactive cross-sections, mapping, log plots, cross-plots, custom
spreadsheets, horizon and fault picking, trace processing and mathematics, and
synthetics.
You can easily build full coverage maps for
Petra
projects with BigTopo7. Let’s build and register a basemap for the Petra
Tutorial Project.
Maps exported from BigTopo are ‘UTM Projection’ so
first set the
Petra
project projection to UTM. Select the main menu option “Project: Settings…:
Set Map Projection…”:
On the
Petra
‘Map Projection Settings’ dialog choose:
‘UTM (Northern Hemisphere)’
Next check the U.T.M. Zone Number. The Petra Tutorial
Project is centered around 29.5 N 95.0 W and the natural UTM Zone is 15. If you
don’t know the correct UTM zone for your project, BigTopo will display the
correct zone when we make the coverage map and you can return to the ‘Map
Projection Settings’ dialog and match the basemap.
Next select the Petra Ellipsoid. If plan on exporting a
NAD27 datum map from BigTopo set the Petra Ellipsoid to ‘Clarke 1866’ (NAD83
= ‘GRS80’):
Press the [Save] button, then press the ‘Mapping’
toolbar button to display the
Petra
mapping module.
Petra
will display the extents of the current project. Select the Map menu option
‘Display: Show Map Limits…’:
Petra
will display the geographic limits of the current project:
In this case the
north west
corner is ‘29.597 N 95.038 W’ and the south east corner is ’29.560 N
94.993 W’. Since we know the project extents, we can use BigTopo to build a
single base map for the project. Start BigTopo7,
Uncheck the ‘Recolor’ option on BigTopo’s
‘Annotation’ tab, lock the ‘North West Corner Coordinate’ and enter the
project extents into the
North West
and South East coordinate boxes. BigTopo will automatically compute the width
and height.
Note that once the
North West
and South East coordinates are entered, BigTopo displays the UTM Zone number in
the center of the green box (in this example it is Zone 15.)
Select the ‘Output File’ tab, select the ‘Export
BigTopo as generic graphic picture’ option, choose an appropriate filename and
path. Set ‘Compression’ to ‘TIF 8-Bit Packbits compression; $2’. (
Petra
can not read LZW compressed TIF images.) BigTopo7 will automatically write a .TFW
worldfile which
Petra
will use to place the base map under the project.
Click on the ‘Build BigTopo’ tab and press the ‘Make
BigTopo’ button to build the basemap. Close BigTopo.
In the Petra Map tool, press the toolbar button ‘Add
Image’:
Then use the mouse cursor to draw a box anywhere on the
drawing. The box position and size are not important.
Petra
will display the ‘Overlay Image Attributes’ dialog.
Press the ‘Browse’ button to prompt with the ‘Select
Image File’ dialog, browse for the basemap file and press [Open]:
Select the ‘Options’ tab (on the ‘Overlay Image
Attributes’ dialog), then press the [Select File] button and browse for the .TFW
worldfile:
Press [OK] and
Petra
will load the basemap, place it in the correct place under your vector
annotations.
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