# Homework Help: Remote Sensing

1. Aug 27, 2007

### Huma waseem

After studying a little bit about the remote sensing i have a Question to ask that If i have a object inside the earth, on the earth at rest and on the earth which is moving how can i determine my Object on the earth?What sort of difference may i have to make in my satellite that to observe such different type of the Objects.... and if any object is moving and i am not taking aerial photographs of them how can i differentaite between moving and Rest object?
what will be the shape of my spectrum and how could i make it possible for my satellite to assosiate some color with that particular object.. let suppose i have to detect a person in the earth say any terrorist etc so what will the first thing i will assosiate with that person to detect him.... either a color of some specific wavelength but it sounds so confusing that to do that isnt?may be possible that same radiation may be emitted by some other object that time....
plz help me it is very confusing for me ....

2. Aug 27, 2007

### mgb_phys

I will try and understand.
Remember remote sensing means much more than just satelite photographs.

Usually the images are still photographs, to show an object is moving you would take a photograph of the same area later and see what has changed.
There is a google earth image showing multiple images of the same plane landing at an airport.

You can use different wavelengths to tell the difference between different materials. Usually infrared is used because water has a strong effect in the infrared and so it can be used to show where plants are growing and different kinds of plants.
Although spy movies show infrared heat from a person, remote sensing satelites wouldn't pick up such a small signal. Although they can spot if a ships engines are running or heat from vehicles. It is easy to spot a person on infrared from an aircraft.

Recognising objects from poor resolution satelite images especially taken under bad weather conditions or from odd angles is a real art - goverments have experts who have spent years learning this, it isn't like in the James Bond movies!

Last edited: Aug 27, 2007
3. Aug 27, 2007

### Huma waseem

so it means we take a couple of pictures to make it sure the particular object is moving after some time ... Ohkey !
Sir but if the object is inside the earth and on the earth what should be the right choice of selecting the wave for them and for Weapon and Mines detection i think it is related to to millitay satellites... i have seen somewhere the hyperspectra satellite also use in millitary purpose.... i have heard that if i have to drop a bomb on certain target i use pictures via remote sensing satellites and they exactly drop there.but the problem is still there how to Determine the Target on Earth Via Remote sensing satellites ... and how will i know that if i am getting say Dark Blue at some spot so that is that target which in i am interested,how can i Give such information to my satellite ...?????

4. Aug 27, 2007

### mgb_phys

Satelites don't see INSIDE the earth.
It is sometimes possible to find things under the earth from pictures, you can find archeology by seeing where crops don't grow as high because there are old stones under the ground.
Satelite pictures are just used as maps to decide where a target is, the satelite doesn't drop bombs on them and there isn't a particular color of targets.
And you have to be careful, the USA accidentallly bombed the chinese embasy in one country because the real target had moved house to a different address - a satelite cannot tell you that!