Contour line issues

[OvidiuFrantescu]

Hi all,

I am working with a raster file (.tif) that I have georeferenced, and now I would like to extract the contour lines of of it.

After using the contour tool I am left with multiple lines representing a single contour line from the raster.

Basically the tool does not recognize only the center-line of the contour line from the raster to generate an unique line (see attached image).

How can I condense these lines, or generate a single (center-line) one.

Thank you,

Ovidiu

[curtvprice]

If you can manipulate your contour raster into binary (1/0 or 1/nodata, where 1 are the contour line cells and 0 are the background) you can use automated methods in ArcScan. Worth looking into if you think it will save you time. These automated methods require that your raster is easily manipulated into this two-color format - Photoshop or GIMP expertise are helpful for this task.

What is ArcScan?—Help | ArcGIS Desktop 

[OvidiuFrantescu]

Curtis,

I have ended up playing around with this extension, and it worked nice, especially the snap to raster function, but then it stopped working. After restart I could not make the ArcScan to recognize the raster so I can continue to digitize while snapping to the raster

I reclassified the raster to two values, 1/0, with 1 being the contour lines, and that is where I started.

Thank you,

[NeilAyres]

<Columns_and_Rows> 30001, 28766

<Number_of_Bands> 3

<Cell_Size__X._Y_> 0.013888889, 0.013888889

<Uncompressed_Size> 2.41 GB

<Format>TIFF

<Source_Type>Generic

<Pixel_Type>unsigned integer

<Pixel_Depth>8 Bit

<Colormap>absent

<Pyramids>level: 7, resampling: Nearest Neighbor

<Compression>LZW

<Mensuration_Capabilities>Basic

<Status>Permanent

<Extent><Top> 399.527777778 <Left> 0 <Right> 416.680555556 <Bottom> 0 <Spatial_Reference>WGS_1984_Web_Mercator_Auxiliary_Sphere

That, to me, looks like this tif hasen't been georeferenced at all, just defined as Web Merc

[OvidiuFrantescu]

So here is where I got now,

I started from scratch, captured over 250 print-screens to assemble my tiff raster, after ArcMap import I have georeferenced, projected, and reclassified the raster to display only two colors. Than using ArcScan I have extracted the center-line of each contour and placed them into a new line feature. All that is left now is to do some corrections of the resulted lines. Lots of tedious work for me, but nowhere near as much as digitizing the whole thing.

Thank you all for you input,

Ovidiu