Camera Questions

[Markovitch]

If I take a picture it will be a certain size (size really meaning clarity) depending on features like zoom, light etc. If I want to blow it up and focus in on one particular item blowing up the individual item will result in loss of resolution right?
Lets for example I am trying to fix the location of an item using a satellite image with a scale of 1:2500, panchromatic 0.5. If the item is say a tank I need to know if it is ours or theirs. Blowing up that the part for the image with the tank in it will not simply increase the quality of the image of the tank right? So even if I just keep making the tank bigger and bigger I won't be able to accurately tell the damage an artillery shell has made for example? Being able to say it has penetrated, calculated entrance hole size to say a millimeter? Is there any mathematical relationship between increasing picture size and loss of resolution? I assume its not simply linear?

[griff]

You're generally right Marko. If you think simply of digital cameras that you can buy on the high street which are designed to be carried around, their portability dictates their size. The largest sensors that tend to be used are the same size as an old 35mm film negative, hence "full-frame". Most DSLRs have sensors two-third that size to keep costs down. The quality of the lenses, the software used and the manufacturing tolerances of the sensors (the lenses focus the light on the sensor just as they did on the film negative) all dictate the pixel-rate of the final image. A reasonable DSLR gives summat like 16 to 24 megapixels though they are increasing this as quality can be improved at lower costs and memory costs decrease. Once you have the final image the more you look at certain parts of the image all you see are pixels, or blocks.

The military aren't constrained by high-street considerations like size and cost so they can use (even in satellites) much bigger sensors and the las

[YoouuPiessss]

This thread is way out of my league,I'm happy enough with the camera on my phone...

[Pentridge]

Taz lad is your man tbf Marko.

[Markovitch]

We have access to DigitalGlobe satellite imagery with a panchromatic resolution of 0.5m I believe that is the lowest? GCHQ uses 24 I think. One country might for example claim breach of sovereignty if another country fired missiles at them across the border. The missiles might have been mounted on mobile launchers and the satellite images taken 2 weeks later. So tanks with holes, craters, cigarette papers. What would be the holes in the argument from a photographic pint of view? I can't see a bloody thing from the photos but anything I should know about the process? No military grade for us I'm afraid, classified

[griff]

Google 'Geo-Eye 1' Marko; that Satellite seems to be supplying your imagery to a 20" (0.5 metre) standard from over 400 miles up. You'll probably be looking at images where each pixel equals 20 inches so anything smaller will be lost.

[Markovitch]

Cheers Griff, so why is bigger better? Don't you lose more? If the images are panchromatic is perspective an issue for judging direction? Or does the satellite somehow take that out through the 3d imaging system?

[griff]

Bigger isn't really better unless you're talking in digital terms about more pixels per inch which will increase definition, or more available memory which will allow larger images to be stored and reproduced/viewed more easily. In your panchromatic images you really need what the military are getting - LESS than 50cm blocks. They are already getting an admitted 40cm or so block size with apparently 30cm or so to come from this sort of range. In all probability they're already getting 20cm from the same distance, or 5cm from satellites closer in. Of course these will also carry optics that can give better reproduction than that - see my original post, which is why you will see great quality images with high definition apparently taken from space. That then leads us onto drones, which is an entirely different kettle of fish both for munitions delivery and photography. Just don't tell them you know me, right?