what causes this dem problem?

[geophil]

If that is the hill in question (is it?) how did you create your maps and vector data?

Unless you deliberately fiddled about with the SRTM DEM files, those wouldn't be the ones to blame.

So, what has been your map data source? Google Earth, with placemarks? Or a Map Tile service like Google Maps? I used the latter for my analysis.

 

[misterchugg]

hi geophil

i checked back to an earlier version without much textures
and it had placemarks
it was taken from google earth

is that why it went funny

i thought that a thing like google Map Tile service only gave me road maps style.

i tried that too,
but preferred the G E way with the colorings, roads, rail and white spots for the buildings

i might have to redo everything from scratch after thinking about it.
its way too far out in placement

luckily i'm not too far in seeing that i had a lot of trouble trying to get the right looking ground textures

what would you suggest?

thanks for your help mate
ron

 

[geophil]

i checked back to an earlier version without much textures
and it had placemarks
it was taken from google earth

What can go wrong with placemarks is that they can be positioned out of centre. TransDEM has no way to discover this. TransDEM will detect rotation or tilt but a simple shift will pass through without any complaint. The GE tutorial in the TransDEM manual emphasises the importance of centred placemarks: "Important: Do not alter the view in any form between step b. and completion of step e. It would decouple the placemark from the image."

This would be the plausible explanation for the location error.

i thought that a thing like google Map Tile service only gave me road maps style.

You can switch the type to either "orthophoto" or "combined". Be aware, though, that you may need a number of sessions as Google may prevent downloading a huge number of tiles in one go. It would be faster than GE placemarks nonetheless and also free of geoferencing errors.

 

[misterchugg]

hi mate
thank you so much for the explanation
sometimes i think i must have been too thick between the ears when jerker helped me

i will try it with the combined setting when i get the net to myself after
i reread the tutorial parts that you highlighted

thanks again
ron

 

[misterchugg]

hi geophil

after the 3rd try i got a better result

i still cant get the contour lines like you have though

i think you would agree that these screenshots are looking a lot better

please let me know your opinion
and again, thanks for helping

ron

the road intersection without any placemarks like the earlier ones had.
i still don't know how i got them to go away

 

[geophil]

i still cant get the contour lines like you have though

i think you would agree that these screenshots are looking a lot better

The easiest way is to check the results would be in TransDEM itself. Not much can go wrong between TransDEM and Trainz, georeferencing-wise.

In TransDEM there are three DEM enhancements buttons on the toolbar to the right. The first is for smoothing the DEM when zooming in, good for lo-res DEMs like SRTM, the second is for shading (3D appearance), and the last one is for contour lines.

If the railway course you traced closely clings to the contour lines then you should be all right.

And if that particular hill no longer interferes with your line but is 4km away as shown in my screenshot you will most likely have solved the issue.


PS:

If you really want orthophotos as ground textures then I recommend to use a custom texture set. You can download such a set, contributed by ModelerMJ, from the TransDEM forum site, including instructions. See the Tutorials section there.

 

[misterchugg]

thanks geophil
i will look as soon as i have time
thanks again
ron

 

[misterchugg]

hi

i got the lot from google earth again and i now have this problem

do i need to re-download everything yet again?

thanks
ron

 

[geophil]

What kind of problem do you mean? Low detail?

I think I'll have internet access for two more days. Didn't expect it down here at all.

 

[misterchugg]

hi geophil
no.
the different coloration

reddish on the left and the real sort-of on the right

what would cause this?
did i click on something ?
or could it be google earth?

thanks
ron

 

[misterchugg]

hi mate

over the weekend i tried again with

http://www.nearmap.com/ and

http://www.bing.com/maps/

but these two show the same discolored part

could it be in the satellite ?


thanks
ron

 

[misterchugg]

hi
i tried again with google earth and this is what the main picture looks like

it must have something to do with them

any ideas or suggestions?
thanks
ron

 

[Shortline2]

Hi,

My guess is that the various colors is to tell that the source resolution is different in the various parts, that in some areas you can zoom better in and keep a good look then in the other areas.

That's how I read the image above based on looking at areas before in other places more close to my heart.

Best wishes

Linda

 

[misterchugg]

thanks linda

any idea on how i can overcome this?
its no good to me in surveyor like that.
too hard to see even with my reading glasses on

thanks
ron

 

[misterchugg]

cannot get new dem data from server

hi

i tried for a few days to get the dems again from the map tile severs

i tried ms virtual earth, google maps, yahoo maps, open street map. yandex and even nearmap

with nearmap i was signed in and kept the browser window open, but still no go

i get between 20 to 40 tiles down, then it gives me the follow up map error every time.

i studies the manual and also what jerker had helped me with

still no luck

i tried orthomaps and combined. all without any luck

does anybody have any idea as to what i'm doing wrong?

thanks
ron