Vertical accuracy

[buzz456]

Anyone have any idea how accurate the redem files are vertically? I'm messing around with a little Florida stuff and it's not showing any elevation. Assuming I'm not screwing something up.

[Chacal]

Works as designed.
Florida has no elevation.

[buzz456]

Well not to be snotty but if it shows sea level that means when I put water down it will cover the whole state.

[Bananarama]

Depends on the DEM used, buzz. SRTM for NA can be as much as +~- 30m either way, which is why it's important to obtain the best data available, such as from USGS. Maximum resolution in RW is approximately 8 meters, so if you can get your hands on 1/9 or 1/3 arc second DEM (approximately 3m and 10m respectively), you're in good shape.

[Toripony]

It depends on your data source. 1/9 arcsec accuracy is 3 meters; 1/3 arcsec accuracy is 10 meters. Since a 10 meter variance might leave too much of FL at, near, or below sea level I would assume they've made 1/9 data available???

NED
Source Data Maps/Aerial Photos/Lidar
Source Resolution 3m, 10-m & 30-m DEMs

SRTM
Source Data Radar data
Source Resolution 30-m

[buzz456]

Even three meters is not really going to get at it. I know our house in FL has a elevation of 9.34 feet but much of the town is only six or seven feet. I only know this because there is a flood/hurricane cut off point on the insurance at seven feet. I'll just have to mess around a bit but I did d/l one for some of the keys and they don't show up at all if I'm doing this right. The spot I was trying to get to show was Marathon el. 7 feet and it didn't appear at all. I'll try some up on the main part of the State later.

[dfcfu342]

If your elevation never changes then it didn't import correctly, even flat ol' Florida has terrain deviations. I had to recreate and re-import the .hgt files a second time before my terrain worked correctly. I'm not sure what I did different but it worked the second time

[buzz456]

Well I'm now 0 for 2. Went up near Orlando where there are some more elevation and it worked fine so I'm not sure what the problem is.

[Toripony]

Can you see trash mountain?

[buzz456]

The data is sometimes off by a few feet depending on buildings and trees overhanging by the tracks. You kind of have to go by common knowledge or just what you know about the area.

For instance in a route I'm working on for steam I had to almost completely change the terrain by the tracks to match the prototype. This happened because there was a retaining wall right next to the tracks and the terrain was just a smooth slope rather then a 90 degree drop.

You will have to tinker with it a bit but with the right reference you can get it close

That's all very good but what has it got to do with my question?

[fecrails]

Anyone have any idea how accurate the redem files are vertically? I'm messing around with a little Florida stuff and it's not showing any elevation. Assuming I'm not screwing something up.

Disclaimer: I have close to zero experience with route building, so take my comments with a grain of salt.

I started to experiment with route building several months ago and loaded in some elevation data along the FEC near the town of Jupiter. I thought the topography there would be a good test because by South Florida standards there is some decent height variations as well as some water features in that location. After a great deal of trial and error, I was able to get the topo data loaded and it worked very well. The ocean and tidal rivers all were at 0m, canals upstream of control structures rendered at their proper water levels, about 3m in that area and the average flat land areas were at about 4m which is correct for that area. Highway overpass embankments were some of the more prominent 'hills' and were clearly visible and rose to their correct heights of 8-10m. In many places the railroad embankment as well as the associated ditch were rendered quite well!

Now the bad news. I would show a screenshot but all of my work is gone. Long story short, the company I contract for announced a major new IT rollout later this year which includes Windows 8.1 and TPM hardware. I'm responsible for our local network and had zero experience with Windows 8.1. I raced out last weekend, wiped my Bootcamp partition clean of Windows 7 (including TS14 :-( ) and loaded Windows 8.1 to begin my journey to hell! I'm not real fond of 8.1 thus far. What the hell was Microsoft thinking???

[buzz456]

Well I failed miserably at the whole exercise.

[fecrails]

Well I failed miserably at the whole exercise.

No, it took me many trial and error attempts to get results. I wish I could walk you through the process, but all my TS software is on ice. After I get up to sped with 8.1 and reload all of my TS programs, I'll be happy to help you out with it Buzz.