Generating raster data street name coordinates & which projection to use.

470360

Dear everyone

I am about to start the process of generating street name attribute data coordinates for previously georastered raster maps. I am doing this by creating shape files over the pixel areas containing the roads in ArcGIS and then converted the shape files to SDO using the conversion program Shape2SDO. Each shape will be linked to a street name. Does anyone know of an easier way to generate this information, possibly using Oracle itself?

The raster data itself is projected using an obsolete projection as that was the projection used by the map which all maps were then georeferenced to. However when the maps are eventually viewed by users, they will be reprojected using a modern projection, so that users will understand the coordinate system in use. The users will be interacting with the maps via their Web Browser, with the maps served using MapViewer.

I am not sure whether I should store the street name coordinates in the coordinate system using by obsolete projection or whether I should use the modern projection that users will be viewing the maps in. Does any one have any views as to which would be easier to work with when creating the PL/SQL programs.

Kind regards

Tim

Ivan Bush

Tim,

I do not know where in the world you are but I would fiirst check whether the data you require is already available. It will save you a lot of time and aggravation.

If not then I would get your raster map(s) reprojected to the required projection. Having done this you can capture your street attributes. This will mean that the data you store will be in a map projection which your users will understand.

Regards.

Ivan

Ivan Bush

Tim,

I do not know where in the world you are but I would fiirst check whether the data you require is already available. It will save you a lot of time and aggravation.

If not then I would get your raster map(s) reprojected to the required projection. Having done this you can capture your street attributes. This will mean that the data you store will be in a map projection which your users will understand.

Regards.

Ivan

470360

Hi Ivan

Thank you for your reply. I can reproject my maps very easily in ArcGIS, so I will do that. I am planning to reproject the raster maps themselves using spatial but only for the viewing of the maps. The actual maps will stay stored in their original georeferenced projection.

I wasn't 100% certain whether it would be easier to program in Oracle if the index coordinates matched the stored map coordinates but I imagine it doesn't matter if the maps are to be reprojected.

Data may exists for some of what I am doing. However even if it does exist, I am wishing to work with my own copyright. This means I cannot use anyone else's data unless it's available copyright free, which for what I am doing, won't be the case.

Although I am starting to do the coordainte generation using ArcGIS, I would be interested if anyone knows a way of doing it using Oracle.

Kind regards

Tim

Ivan Bush

Tim,

I mentioned looking for the data because I have found data for projects I have been doing available without copyright or charge on the web. It is always a good start.

I do not know if there is a way of doing this in Oracle. However you can use ArcGIS and put the data straight into Oracle Spatial using a direct connection. If you have access to a GIS then I would recommend using it to do your data capture as that is one of the main functions of GIS.

Regards.

Ivan

603401

Tim, Ivan,

Another options to get Spatial data in and out of Oracle and do re-projection is by using the GDAL (www.gdal.org) command line tools.

Examples:

ogr2ogr -f OCI:user/[email protected] roads.shp
gdal_translate -of gtiff georaster:user/[email protected],tab,col,id=1 scene.tif
gdalwarp -t_srs '+proj=utm zone=11 datum=WGS84' scene.tif scene2.tif
gda_translate -of georaster scene2.tif georaster:user/[email protected],tab,col,id=1

Ivan (Lucena)

470360

Dear Ivan

Thank you for your second reply. I am now working in ArcGIS or attempting to at least. I've used ArcGIS before but I've never tried to create shape files for a pre-existing table before.

I have considered doing the work in MapInfo, which can link directly into Oracle but as all the maps were georeferenced in ArcGIS, I prefer the georeferencing interface ERSI use, I'm looking at doing it ArcGIS for the moment.

There is openstreetmap data (www.openstreetmap.org) for the area I am working on but I don't know enough about converting openstreetmap data at the moment. In addition to that some of my maps did not georeferenced very well, source material was not drawn to scale, so they wouldn't even match the roads as displayed by openstreetmap.

I could use UK post office or Ordnance Survey post code data but copyright aside, even that wouldn't be that good because a post code does always refer to just one street in the UK or even a whole street in some cases. There are features such as parks which may have no post code information. Even if they do, the water features such as rivers will not have the information attached. Again georeferencing problems may be an issue here.

Regards

Tim

Ivan Bush

Tim,

I did not realise you were in the UK.

I took a look at OpenStreetMap and it exports in XML so that is not too difficult to get into Oracle.

Drop me an email at ivanj dot bush @ environment-agency dot gov dot uk and let me know what data you are after and I may be able to help.

Regards.

Ivan