About Grids and Images

In Oasis montaj, grids and images are displayed on a Map in the Map window.

Grids appear in the Project Explorer under "Grids". Opening a grid opens a view of the grid in its own Grid Viewer window. A grid view cannot accept any graphics that a map can. It can be saved as a map, in which case the map will appear in the "Maps" section of the Project Explorer .

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, click here.

What is a Grid?

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.

What is an Image?

There are two types of images in Oasis montaj: raster images and vector images.

Raster Images

Raster images or bitmap graphics (e.g., .bmp, .tif, .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 onscreen 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 onscreen.

Basic Differences between Grids and Images

Grids are defined as files containing location (X and Y) and data (Z) values. Values are typically interpolated to create a regular and smoothly sampled representation of the locations and data.

Images are defined as files containing location (X and Y) and colour values. Values are not interpolated. Examples of images are standard PC-based raster graphics, such as Windows bitmaps (*.BMP) or tagged image format (*.TIF) files.

Another key difference is that grids contain data values that can be further processed and manipulated whereas only the colour representation can be manipulated in an image. This is reflected in the user's control of the Colour Tool. When the user edits the colour display of an image, they are only able to adjust the brightness of the layer.

Oasis montaj is designed to handle grids and images seamlessly in terms of importing and exporting them from the system.

"True Transparency"

Oasis montaj supports "true transparency", which is automatically enabled for users who have video cards that support it. For users who don't have true transparency supporting video cards, the "Light Table" display technology is used.

Each group or layer in a map has individual transparency settings controlled from the Map Manager tool. These transparency settings affect both 2D and 3D raster images and vector line work.