misterchugg
Active member
hi
what causes this dem problem?
i have no idea why it comes out looking like this
thanks
ron
what causes this dem problem?
i have no idea why it comes out looking like this
thanks
ron
what causes this dem problem?
- Thread starter misterchugg
- Start date
dragonharh
Acount Deleted
???
what ? huh I don't see anything a bit more detail as to what were spost to be seeing.
what ? huh I don't see anything a bit more detail as to what were spost to be seeing.
misterchugg
Active member
the railway line is going up the side of 2 hills
jayholland
Content Creator
Ron,
Time to get out the dynamite and a shovel....
Is the line supposed to go round the hills? If so, it looks as if you have an error in your co-ordinates somewhere, so the vector map of the line is not matching your DEM properly.
BTW, I have found your cattle for you...
Cheers,
J
Time to get out the dynamite and a shovel....
Is the line supposed to go round the hills? If so, it looks as if you have an error in your co-ordinates somewhere, so the vector map of the line is not matching your DEM properly.
BTW, I have found your cattle for you...
Cheers,
J
misterchugg
Active member
hi craig
from what i can make out, there should be no hills there
will have to go for a drive and check
thanks
ron
from what i can make out, there should be no hills there
will have to go for a drive and check
thanks
ron
Ron,
There will always be a small difference in a DEM file as it is taken with a view of the Earth being Flat which for some years we have known is not true :hehe::hehe::hehe:. This may throw out some land heights slightly or the location of roads and rails etc.
Looking at your image, is it possible that there are mountains/hills there and the track goes around them in the foreground of the image near that road looking thing ?
Craig
There will always be a small difference in a DEM file as it is taken with a view of the Earth being Flat which for some years we have known is not true :hehe::hehe::hehe:. This may throw out some land heights slightly or the location of roads and rails etc.
Looking at your image, is it possible that there are mountains/hills there and the track goes around them in the foreground of the image near that road looking thing ?
Craig
misterchugg
Active member
hi craig
lol hehe
its going to be a farm track when its done
after having a good look at google earth
i have decided to leave the hills and alter the line to run around them in foreground
like you suggest
thanks for the help mate
ron
lol hehe
its going to be a farm track when its done
after having a good look at google earth
i have decided to leave the hills and alter the line to run around them in foreground
like you suggest
thanks for the help mate
ron
misterchugg
Active member
the following screen is what i settled on
its close enough for me
thanks for the help
ron
its close enough for me
thanks for the help
ron
dragonharh
Acount Deleted
very well done
As discussed in another thread there are sometimes discrepancies between the DEM data and mapping which can result in things being offset from where they should be by around 150m. There is a function in Transdem to "shift" DEM once you've identified in what direction and by how much things are off.
What are the geo data sources behind this? What kind of DEM is in use here? What kind of vector data?
150m off, as Vern says, should occur under very rare circumstances only. The cause of such error may lie elsewhere, e.g. in the wrong map projection. And in this case it looks more like an artefact in the DEM itself, not like an error in the vector map. ASTER GDEM in particular has a reputation for peaks and pinnacles like this.
cascaderailroad
New member
I was thinking that also, as very few places on Earth have bimps looking like that
misterchugg
Active member
hi mates
we used the only ones that we could find that covered
the area we needed.
as below
S28E152.hgt
S29E152.hgt
then we tried google earth, bing maps and nearmap
only google earth was good enough
we even tried the roadmap version of each
jerker gave invaluable help to get it right
its ok though, we're getting it there slowly
thanks for all the help
ron
we used the only ones that we could find that covered
the area we needed.
as below
S28E152.hgt
S29E152.hgt
then we tried google earth, bing maps and nearmap
only google earth was good enough
we even tried the roadmap version of each
jerker gave invaluable help to get it right
its ok though, we're getting it there slowly
thanks for all the help
ron
And where exactly is that spot you showed in your first post? Coordinates or place name?
misterchugg
Active member
hi geophil
i will have to wait with the answer till after the weekend
not at home
thanks
ron
i will have to wait with the answer till after the weekend
not at home
thanks
ron
misterchugg
Active member
hi geophil
this is the best that i can do from my sons iphone.
the hills shown on my route are supposed to be here.
the closest i can get from this phone is
-27.951061,152.693263
sorry
thanks
ron
<iframe width="640" height="480" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="http://maps.google.com.au/maps?gl=au&vpsrc=0&ie=UTF8&t=f&ecpose=-27.96105545,152.6907937,1406.79,5.017,37.402,0.012&ll=-27.952558,152.691636&spn=0.009098,0.013733&z=16&output=embed"></iframe><br /><small><a href="http://maps.google.com.au/maps?gl=au&vpsrc=0&ie=UTF8&t=f&ecpose=-27.96105545,152.6907937,1406.79,5.017,37.402,0.012&ll=-27.952558,152.691636&spn=0.009098,0.013733&z=16&source=embed" style="color:#0000FF;text-align:left">View Larger Map</a></small>
this is the best that i can do from my sons iphone.
the hills shown on my route are supposed to be here.
the closest i can get from this phone is
-27.951061,152.693263
sorry
thanks
ron
<iframe width="640" height="480" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="http://maps.google.com.au/maps?gl=au&vpsrc=0&ie=UTF8&t=f&ecpose=-27.96105545,152.6907937,1406.79,5.017,37.402,0.012&ll=-27.952558,152.691636&spn=0.009098,0.013733&z=16&output=embed"></iframe><br /><small><a href="http://maps.google.com.au/maps?gl=au&vpsrc=0&ie=UTF8&t=f&ecpose=-27.96105545,152.6907937,1406.79,5.017,37.402,0.012&ll=-27.952558,152.691636&spn=0.009098,0.013733&z=16&source=embed" style="color:#0000FF;text-align:left">View Larger Map</a></small>
Last edited:
Thank you. So I guess we are talking about this place "Teviotville".
From the Google Earth images I can make out features which could be the alignment of a former railway line. I traced it (blue line).
The only significant hill in the neighbourhood which resembles the one shown in your initial post could be this one south-east, nearly 4km away.
My traced railway line seems to fit nicely to the terrain, with the distinct hill in the distance.
And that distant hill looks plausible, too (SE corner), with the "Teviot Brook" flowing in the valley east.
In case this is the area you mean and the hill in question, it seems that either your DEM or your map/vectors are somewhat out of place. How were they created and combined?
(There is another protruding hill further down south, at -28.055286°, 152.682748°, east of "Bunburra Road" but nothing that looks like a railway alignment nearby, either.)
From the Google Earth images I can make out features which could be the alignment of a former railway line. I traced it (blue line).
The only significant hill in the neighbourhood which resembles the one shown in your initial post could be this one south-east, nearly 4km away.
My traced railway line seems to fit nicely to the terrain, with the distinct hill in the distance.
And that distant hill looks plausible, too (SE corner), with the "Teviot Brook" flowing in the valley east.
In case this is the area you mean and the hill in question, it seems that either your DEM or your map/vectors are somewhat out of place. How were they created and combined?
(There is another protruding hill further down south, at -28.055286°, 152.682748°, east of "Bunburra Road" but nothing that looks like a railway alignment nearby, either.)
misterchugg
Active member
hi mate
i followed the tutorial.
everything fitted and went where it should
again, if it wasn't for jerkers help,
i would not have got that far
over the weekend while i was away i have thought about redoing everything,
but after we talked about it,
it will stay like this
it is close enough
the railway line was shut in 1964 and pulled up
it went from Ipswich to boonah dugandan
thanks for your input
ron
i followed the tutorial.
everything fitted and went where it should
again, if it wasn't for jerkers help,
i would not have got that far
over the weekend while i was away i have thought about redoing everything,
but after we talked about it,
it will stay like this
it is close enough
the railway line was shut in 1964 and pulled up
it went from Ipswich to boonah dugandan
thanks for your input
ron