google earth


Diesel Madman
Hello my name is Ashley. my father an myself are try to figure out how to use google earth but were not quite sure how put a saved image on to the standerd trainz survayor base board. if you know how to use google
earth a step by step guide would be very much appriated:D
with the intention of creating the rather ambitious idea UK rail network minus wales & and scotland
Many thanks
Hi Ashley ,
Don't know if it's any help but I use google Earth for quick reference to positioning details on my route Manchester to the Peak District . I draw quick doodles and then use maps and the rulers in Surveyor to position stuff to the compass so I can link to others who are doing their own specific areas. The WHOLE network? One big job , hope you got a few years cos it'll take some to do that much yourself. Ive covered about 50 miles from Piccadilly going south and that's took 2 years and very detailed ! Think about it - do your area and link up. See my thread in Engineers and surveyors on Manchester & the Peak District for some ideas and pix too .Steve
One method to use Google Earth images in Surveyor is to put them in to basemaps, please read the tutorial here. The DLS link is also on the tutorial page. The only difficulty is keeping all the Google images the same size (between separate Google sessions) when obtaining screenshots.
You will need an photo editing program to crop, etc the google image. I prefer the freeware Photofiltre.
Another option is TransDEM which is payware. It automates many of the steps required if using the Basemap approach, including all the coordinate stuff. Upcoming version 1.3 - available as a beta now - goes even further by acquiring the necessary images directly from the web server, Google Maps style.

TransDEM also shapes the terrain, based on a DEM (Digital Elevation Model = height data map).

I find that Google Maps is much more useful for creating the layout geometry (track right of way, roads, rivers, etc) and then I use Google Earth to help set the textures, vegetation, buildings, etc. Of course setting elevation data is much more difficult this way but I don't have TransDEM nor do I know if any DEM data is available for the routes I create this way.

Peter Ware

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When working with Google Maps and company one should keep in mind that Google Maps maps and orthophotos are shown in a standard Mercator projection (one of those mathematical solutions dealing with the ""Flat Earth" problem).

Often, routes build with the manual Basemap approach will by based on the UTM grid or on the O/S grid (UK). While closely related, standard Mercator and UTM or O/S grid are not the same. Ignoring this may lead to distortion and mismatch. The main reason for distortion is the varying scale of the standard Mercator projection, dependent on latitude.

Does it matter? It depends on the accuracy one wants to achieve. If DEM data is involved, precision becomes somewhat more important. One way around problems is to individually georeference each Basemap and work at large scale. This way errors do not accumulate and one would actually do the same as with Google Earth images.

To illustrate distortion, here is the "big picture" (small scale). The first image shows a map region as presented by Google Maps, MS Virtual Earth or Yahoo Maps.

The second image shows the same region converted to UTM. (Conversion to O/S would give similar results.) Distortion is apparent.

The third image shows a DEM overlay (11 SRTM tiles, the greenish area), also in UTM projection. Both DEM and map adhere to the same projection. If the didn't the DEM wouldn't match.