Raster to vector

Question

Hi everyone, how can I use Descartes raster/vector tools to generate a line map from an aerial image I saved from google earth, to get buildings and roads as lines and polygons? I have tried it but I get the error "No valid images overlapped by area"

fmcallis · Answer

Descartes has the ability to vectorize aerial photographs, but you will need to set up a color mask. For example you can create a color mask including the color for the top of the buildings and then choose the vectorize tool and select the appropriate color mask. If you want to convert using the Color Mask tool, what you have to do is set the color(s) of your lines to vectorize in a mask then use this mask to vectorize. This means that the Vectorize tool will only use the lines that contain this (these) colors.....and as soon as these colors do not exist, the process will stop. The process will include some manual vectorizing and also some cleanup of the line work. Click on the widest line to get the line weight. After creating the color mask make sure Convert Line shows the color mask that you created.

Below are the steps we went through to create the color mask in Descartes.

In raster manager go to tools &ndash; color mask 
 In the color mask dialog right click on &ldquo;temp&rdquo; and select &ldquo;add colors&rdquo; 
 Click in empty space that makes up the background of the image that is not part of the image you wish to vectorize. Then click again to form a rectangle and all colors within this rectangle will be added to the color mask. 
 In the color mask dialog right click on &ldquo;temp&rdquo; and select &ldquo;invert all&rdquo; and all the linework you want to vectorize should highlight

If you want to convert using the Color Mask tool, what you have to do is set the color(s) of your lines to vectorize in a color mask then use this mask to vectorize. This means that the Vectorize tool will only use the lines that contain this (these) colors.....and as soon as these colors do not exist, the process will stop. 
 
 https://communities.bentley.com/products/3d_imaging_and_point_cloud_software/f/contextcapture-descartes-pointools-forum/115047/using-descartes-to-extract-vector-outline-of-raster-data/353288#353288 
 https://communities.bentley.com/products/3d_imaging_and_point_cloud_software/w/wiki/24960/new-color-masks-in-microstation-descartes-v8-cs 
 https://communities.bentley.com/products/geospatial/desktop/f/bentley-map-forum/108042/raster-to-vector-conversion-in-descartes/343699#343699 
 https://communities.bentley.com/products/3d_imaging_and_point_cloud_software/w/wiki/24976/how-to-create-a-color-mask-and-set-multiple-colors-transparent

Raster to vector

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