2003 Goro Adachi
All rights reserved.
Map Projections and Interaction
with maps without understanding their subtle mechanics can easily
lead to inconsistency and confusion. The level of complexity
involved is actually quite surprising. Although probably of minute
significance to the average reader, those seeking to investigate the
Time River system in depth are advised to know the following basic
there are countless ways to express a spherical globe on a
two-dimensional plane, there are many types of map projections.
People use different projections for different purposes.
the Time River overlay scheme, we are forced to use a virtual globe
computer program and nothing less. Conventional maps containing
various spatial distortions are just not suited for the purpose of
this operation – which is to see two or more different
geographical regions in superimposition. We really need the digital
flexibility and precision of a virtual globe to create large-scale
preferably the simulated Earth is an ‘orthographic azimuthal
projection’. It shows a natural-looking globe, but its geometry is
as viewed from infinitely far away. (See Figures A2.1 and A2.2.)
Figure A2.1 Orthographic Azimuthal Projection.
Figure A2.2 Comparison.
the required operation is to just make a map overlay, it doesn’t
really matter whether the virtual globe is an orthographic azimuthal
projection or a truer representation of the earth (i.e. a
perspective view from a fixed point in space), as long as the size,
or distance, is consistent.
if the operation requires you to combine a map with something else
(such as a sky projection or a painting), the globe’s projection
type becomes an important issue, because there would be varying
results depending on the selection.
orthographic azimuthal projection becomes a better choice in this
case because it would eliminate one variable – the distance
between the viewpoint and the earth – in determining the overlay
configuration. This makes the whole process much simpler.
to align multiple maps/globes in superimposition is another
important and tricky issue for the Time Rivers. It turns out that
comparing two areas of the planet separated by a great distance –
especially in terms of latitude – is not as simple as it sounds.
it is imperative that the centers of all the projections used in an
overlay composite would coincide when put in place so that the
spatial distortions are uniform among the maps.
Figure A2.3 How to produce a large-scale map overlay.
(The end product of this example is the ‘Eden
discussed in the Nile Decoded
But this alone still
does not ensure consistency. We
also need to carefully decide where
to place the centers of the projections before bringing them
together, as this would actually produce varying results. (See
Figure A2.4 for a demonstration of this.) This process can be
rephrased as choosing the ‘central meridian’ or, as I like to
say, ‘anchor meridian’.
Figure A2.4 The position of the anchor meridian
(central meridian) affects the overlay configuration.
made clear in the author’s book The
Time Rivers, the prime ‘anchor meridian’ selected,
or detected, for the Time River system is 33°E longitude.
these points should be carefully taken into account when attempting
to replicate, confirm, or criticize findings presented in the book
or the Nile Decoded paper.
The Nile Decoded]
Copyright © 2003 Goro Adachi
All rights reserved.
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