Photoshop:

The steps to create the first land of the giants image:

Firstly i had to create the image that is in the billboard. I did this by duplicating the half a mower to complete one full mower. Then i smoothed out the lines to create a more realistic looking image. After that i cut out the car and moved it into the billboard image. I also did this with the scared person. To finsih off the image i added grass infront of the human and car. Next i had to place the mower image in the billboard. I did this by placing a layer mask on the inside of the billboard and dragging the mower image across onto the page. To finish i moved the mower image to scale so it could fit correctly in the billboard.