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XYZ Data
Gridding Methods

Size of Input Data Set

Grid Maps
Image Maps
Shaded Relief Maps
Vector Maps
Wireframe Maps
Adding Drawing Objects / Symbols

The Importance of an Object Manager

Variogram Modeling
Conclusion

 

Hit Counter

 

Image Maps

Image maps are raster maps based on grid files. These maps represent Z values (e.g. elevations) with user specified colors. Blanked regions on image maps are normally shown as a separate color.

The mapping from the Z value to the color is normally defined interactively and can be set by the user. A novel and effective method is to assign specific colors to specified Z values using color anchor points within a pop-up dialog box, as is the case with Surfer. You can add color anchor points at any Z level. Each anchor point can be assigned a unique color, and Surfer automatically blends colors between adjacent anchor points to produce a smooth color gradation over the map.

It's handy if the color schemes for image maps can be saved for re-use later. If this is possible (as it is in Surfer) then the colors defined for one image map can be used with any other image map. In Surfer, since the color anchor points are stored as a percentage of the grid data range, a single color spectrum file can be used for multiple maps, even if the associated grid files cover significantly different data ranges. This is a wonderful feature to find in reasonably priced, off-the-shelf  software!

Another important feature to have in visualization software is the ability to combine image maps with other maps in "map overlays". Image maps can normally be scaled, clipped, or moved in the same way as other types of maps. 

When a coarse grid (a grid with relatively few rows and columns) is used to generate an image map, all pixels within a single grid square are assigned the same color. This can result in an image map with a very blocky appearance. The software "Surfer" uses a pixel interpolation routine with coarse grids to create a smoother appearance.

When a dense grid (a grid with relatively large numbers of rows and columns) is used, little difference is seen between the final image maps whether a pixel interpolation algorithm is employed or not. For dense grids, therefore, on-screen drawing time can often be reduced by turning off any pixel interpolation.