= Stage 3 - Increase Resolution =

Here is an illustration of the general process of Stage 3.

{{attachment:stage3_figure.jpg||width="700"}}

'''Figure 00: Block Diagram for Generation of Subregion Maps'''

In Stage 3 you will use several automated processes to craft subregions using [[bigmap]], tile that bigmap with higher resolution maplets and then process them until the topography becomes stable (i.e., does not change much between iterations). Bigmaps are flat maps of a section of the shape model.  They allow you to focus on a specific section of the shape, which decreases the number of data files being processed.  Bigmaps are also 2D rather than 3D, allowing for easier display and analysis than the full shape model.

The following table shows the blocks, the procedures and the programs used to complete Stage 3:
 
'''Table 00: Procedures for Subregion Map Creation'''

||'''Block'''||'''Procedure Name'''||'''Executable'''||
||[[Block 6B - Bigmap Tiling V0|Block 6B]] || Bigmap Tiling ||[[bigmap]], [[map_coverage]], [[make_tilefile]], [[make_scriptT]], [[lithos]]||
||[[Block 5 - Iterate V0| Block 5]] || Iterate || [[lithos]], [[make_scriptP]], [[lithosP]]||
||[[Block 7 - Clean V0| Block 7]] || Clean || [[residuals]] ||


The goal of stage 3 is to increase resolution, which requires creating numerous additional maplets. You do this by tiling a bigmap with more maplets. Typically, you  define a region of the surface with a bigmap of 1000 x 1000 pixels (OSize = 500). The scripts then produce input files for lithos that create new maplets every 50, which generates about 360 new maplets. The resolution for the maplets is set to create at least 25-30% overlap.
 
You will iterate these products until the error among the maplets is low.  Iteration consists of running Step 3-5 “Batch Topo” numerous times.  Next, you will use the criteria in Step 3-6 “Evaluate” to indicate where there are problems with the shape model and what needs additional attention.  When the residuals become small and the delta correction in the topography becomes small, or if met the navigation requirement, you will output the complete model. Maplets that have problems will go through Stage 4 - Problems.