Color contoured heatmap overlay from raw data on Google maps demo for GM API V3 2023

V1.1: add initial map zoom
V3.0: update for google maps V3 API, add fit to screen option and auto-resize of generated map

Type or paste 3 columns without a header line:

Columns should be separated by blanks or tabs, not commas.

latitude longitude data

resolution of overlay grid (number of color cells)

x res:

y res:

lower cutoff* [0.0 to 1.0]:

blend exponent:
   should be greater than zero
   typical good values to try are 1.5 to 30
   lower is smoother, global effects
   higher lets through more noise, local effects

map size (pixels): X
fit to screen instead

initial map zoom:

Map will be centered at the mean of the lat/long values.

Notes:
- x res and y res are limited to 60, for 3600 total color cells
   we may increase this limit in the future
- all columns of data should be numeric values

- *use lower cutoff value to avoid display of contour data which fade to zero
   such as over large bodies of water. This value should be
   given as a value from 0 to 1. Experiment to see the effect of this
   parameter with your data set. Set this value to 0 to display
   the full rectangular contour.

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