Orthophotography

I work for a county planning department. We have aerial photographs of our county going back to the 1910's.

I understand that FE theory says that GIS companies are in on the RE conspiracy.

However, without using GIS software, with just my scanner and a ruler I can see that aerial photographs taken before the invention of orthophotography are not accurate.

If the Earth is flat, then why are pictures taken with a lens that is designed to account for a round earth more accurate?

An orthophoto or orthophotograph is an aerial photograph geometrically corrected ("orthorectified") such that the scale is uniform: the photo has the same lack of distortion as a map. Unlike an uncorrected aerial photograph, an orthophotograph can be used to measure true distances, because it is an accurate representation of the earth's surface, having been adjusted for topographic relief[1], lens distortion, and camera tilt.

How does this compensate for the curvature of the earth again? 

I can't use Aerial photos that were taken before the 1950's to make accurate maps that have one consistent scale. They are distorted. A technology called orthophotography was developed in the 1950's. I'm a planner, not a photographer, but from what I understand, the lens is constructed to compensate for the curvature of the earth.

If the Earth is flat, then why do we need special cameras to take accurate pictures of it?

Put another way - Aerial photographers take all the photos in one set at the same distance from the ground. If the earth is flat like my kitchen floor, the photos should come out like floor tiles and I'd just have to line up the landmarks that overlap to get a scale map. But that's not what happens. The pictures are distorted. You can see it using a ruler.

The orthophotos are accurate.

If I scan the pictures taken with the old cameras and line them up and then tell the computer to adjust for what RE theory says is the right curve the computer will rectify the photos so that the become not only one seamless gif - but an accurate scale map.

So my question for the FE theorists is, if the Earth is flat, why don't my older aerial photos create a scale map? And why does software that adjusts the photos to account for a round earth create an accurate scale map?

I would guess they don't fit to make an accurate map because they aren't

Quote from: http://en.wikipedia.org/wiki/Orthophoto

adjusted for topographic relief[1], lens distortion, and camera tilt.

It would appear the distortion of the older images is due to insufficiencies in the process of taking the pictures at that time, not to the curvature of the Earth.

It would appear the distortion of the older images is due to insufficiencies in the process of taking the pictures at that time, not to the curvature of the Earth.

Photography has been around for very long, and the required shape of a lens can be calculated easily. I'd say the chances are very slim that this is a fault created by photography in the 1950's.

Quote from: Roundy the Truthinessist on April 30, 2009, 01:25:47 PM

It would appear the distortion of the older images is due to insufficiencies in the process of taking the pictures at that time, not to the curvature of the Earth.

Photography has been around for very long, and the required shape of a lens can be calculated easily. I'd say the chances are very slim that this is a fault created by photography in the 1950's.

If correcting the images to make an accurate map was that easy it should be no problem correcting for the curvature of the Earth.  Orthophotography corrects for a great deal that has nothing to do with the shape of the Earth.

If correcting the images to make an accurate map was that easy it should be no problem correcting for the curvature of the Earth.  Orthophotography corrects for a great deal that has nothing to do with the shape of the Earth.

Yes, but if the Earth is flat, correcting for a round earth would make the picures less accurate, not more accurate.

Why does correcting for a round earth make the pictures accurate if the earth is flat?

Quote from: Roundy the Truthinessist on April 30, 2009, 01:51:09 PM

If correcting the images to make an accurate map was that easy it should be no problem correcting for the curvature of the Earth.  Orthophotography corrects for a great deal that has nothing to do with the shape of the Earth.

Yes, but if the Earth is flat, correcting for a round earth would make the picures less accurate, not more accurate.

Why does correcting for a round earth make the pictures accurate if the earth is flat?

Before I try to answer that can you provide a source confirming that orthophotography corrects for a round Earth?

Are you sure it has nothing to do with the amount of atmosphere? There would be a substantial difference between the two vantage points.