Grid-file geoid boundary is distorted

Question: Why is the grid-file geoid boundary shown as a perfectly rectangular box when displaying a job in Geographic but when displayed as Grid it changes to a distorted box with sides not either east-west or north-south?

Answer: The nodes in a geoid grid file are listed as geographic coordinates which define a 'square' grid between nodes regularly-spaced along meridians of longitude and parallels of latitude. When these 'square' geographic coordinates are converted to grid projection coordinates, the area of the grid may not be symmetrically positioned over a grid zone, hence the corresponding eastings and northings will not produce a correspondingly 'square' boundary. In any case, even if positioned symetrically over a grid zone, the easting values for the northern and southern boundaries will not be equal unless the area is also positioned symmetrically about the equator.

Labels: The label positions may not always be plotted close to the lines, particularly when only one boundary line is shown and it crosses right over the plot window; labels are plotted relative to one end of the displayed boundary line and may not appear correctly positioned if the line is skewed in Grid view.

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