Wednesday, February 21, 2007

Estimating the dimension of Google Earth full resolution image

Above my home, the smallest detail I can spot on Google Earth for a pixel is about 10 cm.
The Earth equatorial circumference is about 40 000 kilometers.
This makes 40 000 * 10 000 = 400 000 000 pixels.
Assuming the Earth is spheric and the Google has all data, this makes 400 000 000 * 200 000 000 = 80 000 000 000 000 000 pixels, much more Gigapixels that I can imagine.

Of course I do not think data is available at this resolution for the whole Earth, and my estimation of precision can be wrong, but these numbers are mind-boggling.

The most precise satellite image of the Earth I have is about 1 pixel for 500 meters, this already makes a 86400 * 43200 image.

Wednesday, February 14, 2007

Download the NASA Blue Marble NG pyramidal TIFF

I know seeing is believing. Unless you actually see one gigapixel pyramidal image viewed by VLIV, you will not really understand how nice it is. This is why I have made the NASA Blue Marble NG image downloadable here.

Be warned, it's a large image (427,582,365 bytes). It contains all 8 resolutions from 86400x43200 pixels down to 675x337 pixels.

In order to keep the image size reasonable, an aggressive JPEG compression has been conducted, so there are some artifact you would not experience on lossless compressed image.

Tuesday, February 13, 2007

External libraries and tools used to build VLIV

VLIV is written in pure C (about 3000 lines, not counting resource file). I am using numerous external libraries to load some image types, as well as other tools.

Libraries are:
  • libtiff for TIFF files handling
  • IJG JPEG library for JPEG amd JPEG-in-TIFF handling
  • libpng for PNG handling
  • zlib (indirect usage through libpng) for Deflate compression in TIFF images
  • OWND library for intellimouse handling
External tools I use are:
  • UPX for compacting the VLIV executable
  • NSIS for the installer
All these tools are very well designed, and have saved me lot of time in getting VLIV done.

Saturday, February 10, 2007

What is your largest image ?

The largest images I have on my machine, viewable by VLIV are 86400 x 43200 = 3.7 Gigapixels
(It's the NASA Blue Marble NG) and 96512 x 88832 = 8.6 Gigapixels.

What are the largest images you have been able to view with VLIV ?
Please post them in comments.