I just yesterday ordered some additonal memory for this very task. Next week I will have 2.5 GB RAM.
That's always good if you want to work with images...
The point is, if I wanted to derive that full image could it be done with your tools?
But my nmtools as published so far, are exclusively for making normal maps
to be used in Celestia!?? Didn't you have a look at my detailed tutorial that describes the meaning of normal maps in multi-texture overlay displays?
You still did not describe clearly what you have in mind after the original full-sized 21601x10801 gebco elevation
graymap has been loaded into your computer? Do you know precisely what such elevation maps are and how they have to be used? Note that they DO NOT look like this image I showed in shatters.net:
You did not even tell, whether you are planning to use Celestia for displaying whatever you are out to produce. I can hardly give you good advice without knowing the aim of your efforts.
The original gebco file is a file that contains for each point on Earth the respective elevations as 2 byte
signed integers, such that a height difference of 65536 meters can be described altogether on Earth. Normal viewers including Photoshop are preferably made for 8 bit =1 byte displays, however! Therefore, independently of the file's BIN format such 2 Byte elevation maps cannot simply be displayed in a standard viewer program. In Photoshop you might use special S-shaped curve profiles to do so, but this is really for experts and hard to describe in words.
If you had instead told me that you want to display the results in Celestia
, the story would be entirely different. Celestia can both read elevation graymaps or preferrably normalmaps. If you wanted to reproduce an image as I displayed it in the shatters.net forum thread, it's easy. But I need to know what you want. Instead, as we are now, I am just BLINDLY guessing...
I downloaded the JPG file offered from the NASA Blue Marble site and changed a few things in order to get it to display. It's a whole 21601x10801 and my machines handle it without any problems. The file is a mere 6MB.
But that's obvious, since JPG is a LOSSY format and limited to 1 byte
per channel. So it does compress huge files into MUCH smaller ones. The main point of the JPG file from the snowy server you were referring to is that it has been converted to 8bit = 1 byte level and thus can be displayed in standard viewers.
All I wanted to do (originally) was generate the file myself from the bin file.
Why and to do WHAT with it?
I can understand your confusion, seeing as I already have the 16k version, but really what I wanted to do was get hold of the highest resolution normal map possible, including the DEM for land features as well as the bathymetric data.
Once more, did you read carefully my tutorial about the nmtools and notably section 2) about The Purpose of Noprmalmaps in a Nutshell
?? I am not sure whether you really know what this all means and we seem to be "bypassing" each other...
http://www.forum.celestialmatters.org/v ... c.php?t=18