the fallacy of using shadow size // profile to make assumptions about objects

a bit of a strange thread title - but bear with me - as this is a pet peeve of mine

without pointing any fingers at specific threads or member posts

I not that its a common error for people to make false assumptions about objects [ mostly height and profile ] - based soley on their shadow

now a fortuitous observation on GE will looking for something else - gave me the textbook example I needed to illustrate my assertion

ladies and gentlemen - I give you :

roundhill reservoir dam

picture :



now you can clearly see from the pic that :

1 - the dam top is flat

2 - the area below the dam is both sloping and terraced

now lets look at the shadow this dam creates :



source

now the readers of this thread already know that its a dam - that is low and plat topped - because I have just told you

but its shadow APPEARS to indicate a triangular structure of considerable apex height . NOT a flat structure that is quite low

look at the ends of the dam - the shadow there falls on flat ground

so there you have it - shadow profile does not give a meaningful insite into structure height or profile

The first image, the picture of the dam, is just a very small portion of what's shown in Bing Maps. The map actually shows the entire length of road that goes uphill to the very top of the dam, and then downhill to the other side.

So, while your first image shows just a picture of the dam, it's not showing the entire stretch of road from one side of the reservoir to the other where the triangular slope would be visible.

The shadow covers the entire stretch of road from one side of the reservoir to the other. Not just the dam itself.

a reply to: ignorant_ape
there ya go again with your "shadow fallacies",, using an artificial object to try too debunk said shadows that may or may not have been produced by an artificial object .

a reply to: ignorant_ape

So let me get this straight

The triangular dam makes a triangular shadow

And that debunks using shadows to find the shape of an object

...ok

Well done.

Seems not many so far get the point, I certainly do!

S&F

P

a reply to: Another_Nut

no - the FLAT dam projects a triangular shadow on uneven terrain

the fact that this needs to be explained - then clarified is mind numbing

here is a " triangular dam " forming a straight shadow



source

can you work out why ????

a reply to: _BoneZ_

no - the shadow is projected ONLY by the retaining wall of the dam top road

it is projected into a vee shaped valley

it does not matter that the pic of the dam face does not show the whole dam

the entire structure producing the shadow of the dam is at the same altitude - and that's the retaining wall of the dam top road

the roads on either side of the dam cast no shadows in that pic - you are simply wrong

this is evident - because the wall has pillars at each end which are taller than the wall and which can be seen cast longer shadows than the wall immediately adjacent to it

originally posted by: ignorant_ape
a reply to: _BoneZ_

no - the shadow is projected ONLY by the retaining wall of the dam top road

it is projected into a vee shaped valley

it does not matter that the pic of the dam face does not show the whole dam

the entire structure producing the shadow of the dam is at the same altitude - and that's the retaining wall of the dam top road

the roads on either side of the dam cast no shadows in that pic - you are simply wrong

this is evident - because the wall has pillars at each end which are taller than the wall and which can be seen cast longer shadows than the wall immediately adjacent to it

Some people just do not want to get it.

There is no shadow top left or bottom right of the picture, so claiming the road extends further has nothing at all to do with a shadow!

a reply to: ignorant_ape

Hey buddy don't get upset with me because I point out the flaws in your argument

u posted it

And no I can't work it out... that's why we have computers to do it

reconstruction of objects using shadows

a reply to: hellobruce

sadly - I suspect you are correct - the physics of shadows is not complicated - and can easily be checked by just going outside

I guess this is why it irks me so much - I guess it started for me with the Apollo hoax idiocy of " shadows should be parallel "

all people have to do is go outside and look

a reply to: Another_Nut

there is no flaw in my argument - only flaw is your understanding of basic physics

edt to add - as for your link - did you actually read it ???

it requires a straight edge - ie a known parameter