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| maplet GSD = 10cm<<BR>> bigmap scale = 10cm * 1.5 = 15cm to achieve a 25% overlap |
{{attachment:Eq ol percent.png}} where F is the multiplicative overlap factor, such that: {{attachment:Eq ol factor.png}} For example: To achieve a 25% overlap: maplet GSD = 10cm<<BR>> bigmap scale = 10cm * 1.5 = 15cm |
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| ||0.8||58%||bigmap scale = 10cm * 0.8 = 8cm|| | ||0.8||60%||bigmap scale = 10cm * 0.8 = 8cm|| |
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| ||1.3||33%||bigmap scale = 10cm * 1.3 = 13cm|| | ||1.3||35%||bigmap scale = 10cm * 1.3 = 13cm|| |
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| Example BGMAP1.in: | Example '''BGMAP1.in (for maplets with a GSD of 10cm and a 33% overlap)''': |
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== A Closer Look at GSD Ratio and Overlap == === GSD Ratio - Unity === {{attachment:GSD Ratio Unity.png}} When the bigmap and maplet GSDs are equal, the maplets overlap by 50% and the outer edges of the outer maplets coincide with the edge of the tiling area. === GSD Ratio - Small Overlap === {{attachment:GSD Ratio small ol.png}} When the bigmap GSD is greater than the maplet GSD, the maplets overlap by <50% and the outer edges of the outer maplets lie within the edge of the tiling area. === GSD Ratio - Large Overlap === {{attachment:GSD Ratio large ol.png}} When the bigmap GSD is smaller than the maplet GSD, the maplets overlap by >50% and the outer edges of the outer maplets lie outside of the edge of the tiling area. == The 'Dead Zone' == |
Basic Tiling - Achieving the Desired Maplet Overlap
(compiled by DL)
Purpose: Basic tiling allows the user to generate a suite of maplets at a higher resolution which tile a region of interest. The overlap of the new maplets is controlled by the ratio of maplet ground sample distance (GSD) to bigmap scale. This 'How-To' explains how the user achieves the desired maplet overlap percentage.
Generating a Tiling Bigmap
The user must generate a bigmap which covers the region of interest and whose parameters are set up such that the new maplets will overlap by the desired amount.
Bigmap .in File
The user must adjust the bigmap pixel scale in the tiling .in file in order to achieve the desired maplet overlap ratio. This is done by applying a multiplicative factor to the maplet ground sample distance (GSD) as follows:
where F is the multiplicative overlap factor, such that:
For example:
- To achieve a 25% overlap:
maplet GSD = 10cm
bigmap scale = 10cm * 1.5 = 15cm
Example set of multiplicative factors:
Multiplicative Factor |
Maplet Overlap |
Example for Maplet GSD = 10cm |
0.8 |
60% |
bigmap scale = 10cm * 0.8 = 8cm |
1.0 |
50% |
bigmap scale = 10cm * 1.0 = 10cm |
1.3 |
35% |
bigmap scale = 10cm * 1.3 = 13cm |
1.5 |
25% |
bigmap scale = 10cm * 1.5 = 15cm |
2.0 |
0 |
bigmap scale = 10cm * 2.0 = 20cm |
Example BGMAP1.in (for maplets with a GSD of 10cm and a 33% overlap):
m <- To locate, reference to a map START1 <- Reference map name 49 49 <- Reference map pixel/line location 0.00013 130 1.23400 1000 <- scale (km/pixel), Q size, integer random seed, maximum maplet scale BGMAP1 <- bigmap name 1 <- bigmap program commands .005 .025 1 0 0 1 1 1 1 1 1 0 0
A Closer Look at GSD Ratio and Overlap
GSD Ratio - Unity
When the bigmap and maplet GSDs are equal, the maplets overlap by 50% and the outer edges of the outer maplets coincide with the edge of the tiling area.
GSD Ratio - Small Overlap
When the bigmap GSD is greater than the maplet GSD, the maplets overlap by <50% and the outer edges of the outer maplets lie within the edge of the tiling area.
GSD Ratio - Large Overlap
When the bigmap GSD is smaller than the maplet GSD, the maplets overlap by >50% and the outer edges of the outer maplets lie outside of the edge of the tiling area.