I'm trying to extract the areas with vegetation as a polygon-shape from a landsat7-image, 30m resolution, RGB, using QGis 1.8 or Bilko or (hopefully in the near future) ArcGIS. The area is in Northern Peru, dry season, so basically I want to extract all the shades of green.

I have never really worked with raster data and don't know what to do. I have found out there are "vegetation indices" which can be calculated, and have found Bilko as a software I could do this with. However, if I got it right I need more bands than RGB to do this - is this true? I'm not sure.

On this website I have also found threads on how to calculate vegetation area in QGis - using GDAL tools or SEXTANTE: Calculating area of vegetation in raster file?

However I would like to not only calculate but extract the data as a polygon.

What would be the best way to do this? I've never worked with Bilko, GDAL or SEXTANTE, of course I will go into that and try to learn, but I would like to know what will work before I spend hours and hours only to find out I can't do it...

P.S.: I will probably have ARCGis in a while, so if it is much easier with ARCGis I might wait for that...

I'm trying to extract the areas with vegetation as a polygon-shape from a landsat7-image, 30m resolution, RGB, using QGis 1.8 or Bilko or (hopefully in the near future) ArcGIS. The area is in Northern Peru, dry season, so basically I want to extract all the shades of green.

I have never really worked with raster data and don't know what to do. I have found out there are "vegetation indices" which can be calculated, and have found Bilko as a software I could do this with. However, if I got it right I need more bands than RGB to do this - is this true? I'm not sure.

On this website I have also found threads on how to calculate vegetation area in QGis - using GDAL tools or SEXTANTE: Calculating area of vegetation in raster file?

However I would like to not only calculate but extract the data as a polygon.

What would be the best way to do this? I've never worked with Bilko, GDAL or SEXTANTE, of course I will go into that and try to learn, but I would like to know what will work before I spend hours and hours only to find out I can't do it...

P.S.: I will probably have ARCGis in a while, so if it is much easier with ARCGis I might wait for that...

I'm trying to extract the areas with vegetation as a polygon-shape from a landsat7-image, 30m resolution, RGB, using QGis 1.8 or Bilko or (hopefully in the near future) ArcGIS. The area is in Northern Peru, dry season, so basically I want to extract all the shades of green.

I have never really worked with raster data and don't know what to do. I have found out there are "vegetation indices" which can be calculated, and have found Bilko as a software I could do this with. However, if I got it right I need more bands than RGB to do this - is this true? I'm not sure.

On this website I have also found threats on how to calculate vegetation area in QGis - using GDAL tools or SEXTANTE: Calculating area of vegetation in raster file?

However I would like to not only calculate but extract the data as a polygon.

What would be the best way to do this? I've never worked with Bilko, GDAL or SEXTANTE, of course I will go into that and try to learn, but I would like to know what will work before I spend hours and hours only to find out I can't do it...

P.S.: I will probably have ARCGis in a while, so if it is much easier with ARCGis I might wait for that...

I'm trying to extract the areas with vegetation as a polygon-shape from a landsat7-image, 30m resolution, RGB, using QGis 1.8 or Bilko or (hopefully in the near future) ArcGIS. The area is in Northern Peru, dry season, so basically I want to extract all the shades of green.

I have never really worked with raster data and don't know what to do. I have found out there are "vegetation indices" which can be calculated, and have found Bilko as a software I could do this with. However, if I got it right I need more bands than RGB to do this - is this true? I'm not sure.

On this website I have also found threads on how to calculate vegetation area in QGis - using GDAL tools or SEXTANTE: Calculating area of vegetation in raster file?

However I would like to not only calculate but extract the data as a polygon.

What would be the best way to do this? I've never worked with Bilko, GDAL or SEXTANTE, of course I will go into that and try to learn, but I would like to know what will work before I spend hours and hours only to find out I can't do it...

P.S.: I will probably have ARCGis in a while, so if it is much easier with ARCGis I might wait for that...