Dem'd terrain lakes

[davelong]

Hi all,
Any ideas about whats best to sort out giant holes in my dem'd terrain. Building my route west out of Brum NS towards Wolverhampton, we get very cose to edgbaston resevoir. Now in my terrain there's a huge hole, Any ideas on whats best to sort it out? I do plan on having the water visible at some point.
see below.


Click the image to zoom in


Kind regards
Dave L.

[DarwinS]

Personally I think you are lucky

My demex terrain for lakes and the sea is flat at surface height...
So I have to go around digging holes just so I can fill them with water..

[NansHoosvat]

Hi all,
Any ideas about whats best to sort out giant holes in my dem'd terrain. Building my route west out of Brum NS towards Wolverhampton, we get very cose to edgbaston resevoir. Now in my terrain there's a huge hole, Any ideas on whats best to sort it out? I do plan on having the water visible at some point.
see below.


Click the image to zoom in


Kind regards
Dave L.

Using TStools it is rather easy. If you know on which tile your basin is located, you can select that tile, and simply adjust the water height of that tile, maybe for surrounding tiles if the basin is a huge one, or even a river (I did the THames!). Best water height is the edge of the basin minus 1 metre or a few feet. Correct if the surrounding terrain appears to be inundated....

Regards,

Hoosvat, Netherlands

[LucaZone]

Thats not a Resevior, its far to square shapped and has corners that the 90m data wouldnt have been able to record. In MSTS it would look like any other piece of terrain. The measurements from the satelite would have bounced off the surface of the water, so it would appear flat. For the Channel in my route i can make out waves on the surface.........

If however you want to use this hole as your resevior, then its a simple case of taking the F9 tool and smoothing it out but dragging a suitable selection area and pressing F as you move the mouse around

There are a number of 'black Hole' style dips in my terrain too, you just need to smooth them out.

[davelong]

Well what i did was look up the co ords.in RE then looked them up on a number of websites, all said it was slap bang in the middle of the resevoir.

thanks
Dave l.

[ccsdc]

I found quite a few places where there were big holes in the 90m DEM data when I was doing Thames-Mersey. The worst was just North of Colwich I recall where there was about 1/2 mile of DEM missing, so I just manually terraformed these missing areas.

In this example, if you do not want a lake there, simply use the terrain tool to select the area and right click and select flatten, that should get rid of the hole.

Dave

[qzdcg8]

Me too - there's the odd hollow in DEM'ed Woodhead

[NansHoosvat]

I don't have a map of the area, so I cannot make out if there should be a reservoir or lake there. I only remember having seen a very similar structure after I DEMmed the London area. At first I took it for an artifact and removed it. Later I discovered that I had removed the Brent reservoir (Welsh harp). Then I reDEMmed the tile. Afterwards it turned out to be extremely useful to correct the map overlay, which was wrong a few hundred metres. After correction I found more of these lakes: all in their right places.

Hoosvat

[qzdcg8]

Me too - there's the odd hollow in DEM'ed Woodhead

Just occurred to me - the first bit of track I relayed on DEM'ed Woodhead was alongside all the reservoirs up the valley and NONE of these had huge depressions in them - there was just a wide flatness in the base of the valley

[Christopher125]

Hi

I think it must be variable. For example, the only depressions on the GCR I found was... slap bang where swithland reservoir was. However, I think the water might on windy days cause cause the waves to be distorted enough for it not to register with the satellite, thus why the holes are so deep and why they are square-ish. However on calm days they reflect normally. Also, this has to do with the differing speeds of waves in air and water.

Just a thought.

Chris

[jains15]

Hi

I think it must be variable. For example, the only depressions on the GCR I found was... slap bang where swithland reservoir was. However, I think the water might on windy days cause cause the waves to be distorted enough for it not to register with the satellite, thus why the holes are so deep and why they are square-ish. However on calm days they reflect normally. Also, this has to do with the differing speeds of waves in air and water.

Just a thought.

Chris

That coincides with my theory, some sort of anomoly at the time the DEM data was taken currupted the lakes DEM, and therefore caused it to register as a massive hole.

Or it's simply a coincidence, as holes like this manifest themselves all over DEM terrain. I can think of about 5 on my route. It's interesting that these are always 'holes' and never 'towers'.

jon

[LucaZone]

It's interesting that these are always 'holes' and never 'towers'. jon

Ive had a few towers. Especially in urban areas. Like the DEM hit a building top or something.

[jains15]

Ok i stand corrected!

Did somebody not say that the forth bridge shows up on the 90m DEM?

[7andY]

Did somebody not say that the forth bridge shows up on the 90m DEM

...both Severn Bridges do, so I wouldn't be surprised!!

Cheers, 7&Y

[drewdrake]

When I DEM'd a route with reservoirs the terrain height is at the bed of the reservoir. It was then easy enough to raise the water level until the shape of the reservoir looked right. But an earthwork embankment dam, which had a 600ft thick base, didn't show up at all.