The default settings will simply render a geocentric full moon in fast render mode 1, as
shown above.  By simply changing a few numbers in the SCENE DEFINITION PANEL, we
can render a customized lunar scene from virtually any perspective we choose.

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This example will render a view of Mare Crisium (Sea of Crises) as viewed from about
4777 miles from the center of the moon or about 1/50th the mean lunar distance
and later, we'll move in even closer.

Mare Crisium is the dark region identified in the geocentric image below.



The first thing we need to do is move Mare Crisium into the center of the view.
To do this, we need to move the camera or eye to the right and slightly upward.

Changing the following source code lines from:

// Move Camera.
  #declare CamMoveLRX = +0000; // -Left / +Right
  #declare CamMoveUDY = +0000; // -Down / +Up

to

// Move Camera.
  #declare CamMoveLRX = +0550; // -Left / +Right
  #declare CamMoveUDY = +0250; // -Down / +Up

will move Mare Crisium into the center of the view. 
The numbers represent miles the camera/eye is displaced in space.



Rendering the adjusted view, should result in the image above, centered on Mare Crisium.

Now, change the render mode from:

  #declare RenderMode = 1;

to

  #declare RenderMode = 2;

RenderMode=2 with Antialias_Threshold=0.0 will produce
the finest quality rendering for the selected image size.


Now, let's zoom in by a factor of 4x by changing the following source code lines from:

  #declare CamZoom = 1.000;

to

  #declare CamZoom = 4.000;

Now, rendering the scene will produce the image shown below.



We can now see Mare Crisium very nicely centered in the view.

Notice that we only changed four numbers in the default SCENE DEFINITION PANEL
to get this far from the default full moon view.

Now let's go a step further and move to 1/50 of its actual geocentric distance
(about 4777 mi from the center) and view the same region from there.

Change the following source code lines from:

  #declare CamDist = 238856;

  #declare AutoFOVSwitch = "OFF";

to

  #declare CamDist = 238857/50;

  #declare AutoFOVSwitch = "ON";

The AutoFOVSwitch (Auto-Field-of-View switch) is a special feature.  This setting is mainly an attempt to automatically adjust for very close-up cam/eye distances and reduce pixelation.

In this case, it is needed because we moved in very close to the moon, less than 5000 miles
from the center of the moon.

Now, rendering the scene will produce the image shown below.



An image of the moon as viewed from Earth, magnified 50 times, whould be somewhat
different than as viewed from 1/50th mean distance, due to the 3D perspective change
between the two locations, like the difference between the two images above, which are
rendered at distances of 238857 miles and 4777 miles respectively from the lunar center.

As we got closer to the moon, less and less of its surface would become visible and
Mare Crisium would move towards the edge and eventually move beyond the horizon
and out of view as we approached towards the center of the current view.

Change the distance to 2000 miles, render, and compare the view above to the view below.

// Camera distance in miles from center of moon.
  #declare CamDist = 2000;

Moving to some 2000 miles from the center of the moon shows the perspective
change quite clearly as Mare Crisium is now even closer to the lunar limb.

Mare Crisium would eventually move beyond the lunar
horizon and out of view.

If we continued forward, reducing the distance to 1250 miles, renders the view below.

// Camera distance in miles from center of moon.
  #declare CamDist = 1250;

NOTE: The distance from the center of the moon must be greater than its radius
or it will result in a fatal program error.



From only 1250 (1250 − 1080 = 170) miles above the surface, Mare Crisium is now
almost entirely beyond the east northeastern lunar horizon from the center of view.