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Tutorial 2: Working with Data
Displaying Grids and Images on a Map
In
Oasis montaj
, grids and images are always displayed on a map in the Map window.
There are several types of grids and images you can display. For a complete list of the
grid and image formats that are supported in
Oasis montaj
see the online help topic
Data
Formats
In
Oasis montaj
, a
Grid
is a visual representation of a survey area interpolated from a
series of survey points. For example, magnetic survey data are collected as a series of
point values organized using a number of lines and arranged in a grid pattern.
When you create a grid,
Oasis montaj
takes these point values from the database and
interpolates between them, creating a visual representation similar to a contour map.
However, instead of simple contour lines, colours and shading are used to represent the
magnetic differences across the grid.
There are two types of images in
Oasis montaj
,
Raster
and
Vector
images.
Raster Images
Raster images or bitmap graphics (.bmp, .tif, and .jpg) are created from a series of pixels
to represent graphics. Each pixel in a bitmap image has a specific location and colour
value assigned to it.
Bitmap images are resolution dependent—that is, they represent a fixed number of pixels.
As a result, they can appear jagged and lose detail if they are scaled on-screen or if they
are printed at a higher resolution than they were created for.
Vector Images
Drawing programs such as AutoCAD create vector graphics (.dxf, .eps, .wmf), made of
lines and curves defined by mathematical objects called vectors. Vectors describe
graphics according to their geometric characteristics. The
Oasis montaj
CAD drawing
tools (licensed version) enable you to draw vector lines and shapes.
A vector graphic is resolution-independent—that is, it can be scaled to any size and
printed on any output device at any resolution without losing its detail or clarity. As a
result, vector graphics are the best choice for type (especially small type) and bold
graphics that must retain crisp lines when scaled to various sizes—for example, logos.
Because computer monitors represent images by displaying them on a grid, both vector
and bitmap images are displayed as pixels on-screen.
D
ISPLAYING A
G
RID ON A
M
AP
1.
On the
Grid and Image
menu, select
Display
and then click
Single Grid
. The
Place a grid on a map
dialog is displayed.
