Select Contour by Length The Next CEO of Stack OverflowRegenerate contour lost partsQGIS raster data from vector and raster filesConnect two contour lines with calculated line lengthAdding intermediate contour values automatically in QGIS?Generate multiple contour lines at specific elevationsContour vs elevation semanticsUsing contour tool in QGIS?Extracting contour lines from ortophoto mapContour TIN InterpolationDetailed contour map
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Select Contour by Length
The Next CEO of Stack OverflowRegenerate contour lost partsQGIS raster data from vector and raster filesConnect two contour lines with calculated line lengthAdding intermediate contour values automatically in QGIS?Generate multiple contour lines at specific elevationsContour vs elevation semanticsUsing contour tool in QGIS?Extracting contour lines from ortophoto mapContour TIN InterpolationDetailed contour map
I am a real beginner with QGIS 2.8. I am able to generate a contour map from a raster DEM, but the contour map is very 'busy' because the land form is pretty flat. There are lots of short contour loops that clutter up the output which would be easy to remove if there was a way to select all contours greater than a certain length. QGIS is able to determine the contour length if I inspect a particular contour line, but this is a 'derived' value, and I do not find a way to use this derived value as a selection criterion.
qgis select-by-attribute contour
asked yesterday
John_BeattyJohn_Beatty
83
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John_Beatty is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I am a real beginner with QGIS 2.8. I am able to generate a contour map from a raster DEM, but the contour map is very 'busy' because the land form is pretty flat. There are lots of short contour loops that clutter up the output which would be easy to remove if there was a way to select all contours greater than a certain length. QGIS is able to determine the contour length if I inspect a particular contour line, but this is a 'derived' value, and I do not find a way to use this derived value as a selection criterion.
qgis select-by-attribute contour
asked yesterday
John_BeattyJohn_Beatty
83
New contributor
John_Beatty is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Welcome to GSE ! Please try to add more context with the DEM source (if possible) and the tools used under QGIS. Have you a particular reason for begin with QGIS 2.8 ? If you want to learn using QGIS, I recommend you to start with the latest LTR 3.4 : qgis.org/en/site/forusers/download.html
– J. Monticolo
yesterday
Can you please explain what GSE stands for.I would start with 3.4 but am nervous of installing programs that haven't made it to my distributions repository
– John_Beatty
yesterday
GSE stands for Gis Stack Exchange, this site ! Since 2.8, QGIS have made great updates.
– J. Monticolo
yesterday
I bit the bullet, upgraded from Mint 18.2 to Mint 19.1 and now have QGIS 3.6 installed. Thank you for your suggestion.
– John_Beatty
2 hours ago
add a comment |
I am a real beginner with QGIS 2.8. I am able to generate a contour map from a raster DEM, but the contour map is very 'busy' because the land form is pretty flat. There are lots of short contour loops that clutter up the output which would be easy to remove if there was a way to select all contours greater than a certain length. QGIS is able to determine the contour length if I inspect a particular contour line, but this is a 'derived' value, and I do not find a way to use this derived value as a selection criterion.
qgis select-by-attribute contour
asked yesterday
John_BeattyJohn_Beatty
83
New contributor
John_Beatty is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I am a real beginner with QGIS 2.8. I am able to generate a contour map from a raster DEM, but the contour map is very 'busy' because the land form is pretty flat. There are lots of short contour loops that clutter up the output which would be easy to remove if there was a way to select all contours greater than a certain length. QGIS is able to determine the contour length if I inspect a particular contour line, but this is a 'derived' value, and I do not find a way to use this derived value as a selection criterion.
qgis select-by-attribute contour
qgis select-by-attribute contour
asked yesterday
John_BeattyJohn_Beatty
83
New contributor
John_Beatty is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked yesterday
John_BeattyJohn_Beatty
83
New contributor
John_Beatty is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked yesterday
John_BeattyJohn_Beatty
83
New contributor
John_Beatty is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked yesterday
John_BeattyJohn_Beatty
83
asked yesterday
John_BeattyJohn_Beatty
83
83
New contributor
John_Beatty is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
John_Beatty is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
John_Beatty is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Welcome to GSE ! Please try to add more context with the DEM source (if possible) and the tools used under QGIS. Have you a particular reason for begin with QGIS 2.8 ? If you want to learn using QGIS, I recommend you to start with the latest LTR 3.4 : qgis.org/en/site/forusers/download.html
– J. Monticolo
yesterday
Can you please explain what GSE stands for.I would start with 3.4 but am nervous of installing programs that haven't made it to my distributions repository
– John_Beatty
yesterday
GSE stands for Gis Stack Exchange, this site ! Since 2.8, QGIS have made great updates.
– J. Monticolo
yesterday
I bit the bullet, upgraded from Mint 18.2 to Mint 19.1 and now have QGIS 3.6 installed. Thank you for your suggestion.
– John_Beatty
2 hours ago
add a comment |
Welcome to GSE ! Please try to add more context with the DEM source (if possible) and the tools used under QGIS. Have you a particular reason for begin with QGIS 2.8 ? If you want to learn using QGIS, I recommend you to start with the latest LTR 3.4 : qgis.org/en/site/forusers/download.html
– J. Monticolo
yesterday
Can you please explain what GSE stands for.I would start with 3.4 but am nervous of installing programs that haven't made it to my distributions repository
– John_Beatty
yesterday
GSE stands for Gis Stack Exchange, this site ! Since 2.8, QGIS have made great updates.
– J. Monticolo
yesterday
I bit the bullet, upgraded from Mint 18.2 to Mint 19.1 and now have QGIS 3.6 installed. Thank you for your suggestion.
– John_Beatty
2 hours ago
Welcome to GSE ! Please try to add more context with the DEM source (if possible) and the tools used under QGIS. Have you a particular reason for begin with QGIS 2.8 ? If you want to learn using QGIS, I recommend you to start with the latest LTR 3.4 : qgis.org/en/site/forusers/download.html
– J. Monticolo
yesterday
Welcome to GSE ! Please try to add more context with the DEM source (if possible) and the tools used under QGIS. Have you a particular reason for begin with QGIS 2.8 ? If you want to learn using QGIS, I recommend you to start with the latest LTR 3.4 : qgis.org/en/site/forusers/download.html
– J. Monticolo
yesterday
Can you please explain what GSE stands for.I would start with 3.4 but am nervous of installing programs that haven't made it to my distributions repository
– John_Beatty
yesterday
Can you please explain what GSE stands for.I would start with 3.4 but am nervous of installing programs that haven't made it to my distributions repository
– John_Beatty
yesterday
GSE stands for Gis Stack Exchange, this site ! Since 2.8, QGIS have made great updates.
– J. Monticolo
yesterday
GSE stands for Gis Stack Exchange, this site ! Since 2.8, QGIS have made great updates.
– J. Monticolo
yesterday
I bit the bullet, upgraded from Mint 18.2 to Mint 19.1 and now have QGIS 3.6 installed. Thank you for your suggestion.
– John_Beatty
2 hours ago
I bit the bullet, upgraded from Mint 18.2 to Mint 19.1 and now have QGIS 3.6 installed. Thank you for your suggestion.
– John_Beatty
2 hours ago
add a comment |
1 Answer
1
active
oldest
votes
There are several way for that
If you just want to select line shorter than 500 you could use $length <500 (or $perimeter <500 if you're working with polygons) as an expression in the select by expression (the 500 is the length in the layer CRS unit, if you want 500m made sure to use a projected CRS whose unit is meters)
Alternatively you could calculate a length field in the attribute table using $length as expression (you could either create a new field (no auto-update if you edit the line but the value are added to your layer) or create a virtual field (auto-update on edit but the value only exist in this specific QGIS project, also usefull if you don't have edit rigth and can't add a new field).
After calculating the lenght you could select or symbolise by attribute as usual
answered yesterday
J.RJ.R
3,546222
Fantastic! Using 'Processing Toolbox' > 'GQIS geoalgorithms' > 'Vector selection tools' > 'Select by expression' and putting in your suggested query I have got exactly what I wanted. Thank you
– John_Beatty
yesterday
Please accept the answer if he has solved your problem, so that other participants understand that a similar question can solve their problem.
– Cyril
yesterday
OK, done. I had to look up on Google to find out how to do this!
– John_Beatty
yesterday
add a comment |
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1 Answer
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1 Answer
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There are several way for that
If you just want to select line shorter than 500 you could use $length <500 (or $perimeter <500 if you're working with polygons) as an expression in the select by expression (the 500 is the length in the layer CRS unit, if you want 500m made sure to use a projected CRS whose unit is meters)
Alternatively you could calculate a length field in the attribute table using $length as expression (you could either create a new field (no auto-update if you edit the line but the value are added to your layer) or create a virtual field (auto-update on edit but the value only exist in this specific QGIS project, also usefull if you don't have edit rigth and can't add a new field).
After calculating the lenght you could select or symbolise by attribute as usual
answered yesterday
J.RJ.R
3,546222
Fantastic! Using 'Processing Toolbox' > 'GQIS geoalgorithms' > 'Vector selection tools' > 'Select by expression' and putting in your suggested query I have got exactly what I wanted. Thank you
– John_Beatty
yesterday
Please accept the answer if he has solved your problem, so that other participants understand that a similar question can solve their problem.
– Cyril
yesterday
OK, done. I had to look up on Google to find out how to do this!
– John_Beatty
yesterday
add a comment |
There are several way for that
If you just want to select line shorter than 500 you could use $length <500 (or $perimeter <500 if you're working with polygons) as an expression in the select by expression (the 500 is the length in the layer CRS unit, if you want 500m made sure to use a projected CRS whose unit is meters)
Alternatively you could calculate a length field in the attribute table using $length as expression (you could either create a new field (no auto-update if you edit the line but the value are added to your layer) or create a virtual field (auto-update on edit but the value only exist in this specific QGIS project, also usefull if you don't have edit rigth and can't add a new field).
After calculating the lenght you could select or symbolise by attribute as usual
answered yesterday
J.RJ.R
3,546222
Fantastic! Using 'Processing Toolbox' > 'GQIS geoalgorithms' > 'Vector selection tools' > 'Select by expression' and putting in your suggested query I have got exactly what I wanted. Thank you
– John_Beatty
yesterday
Please accept the answer if he has solved your problem, so that other participants understand that a similar question can solve their problem.
– Cyril
yesterday
OK, done. I had to look up on Google to find out how to do this!
– John_Beatty
yesterday
add a comment |
There are several way for that
If you just want to select line shorter than 500 you could use $length <500 (or $perimeter <500 if you're working with polygons) as an expression in the select by expression (the 500 is the length in the layer CRS unit, if you want 500m made sure to use a projected CRS whose unit is meters)
Alternatively you could calculate a length field in the attribute table using $length as expression (you could either create a new field (no auto-update if you edit the line but the value are added to your layer) or create a virtual field (auto-update on edit but the value only exist in this specific QGIS project, also usefull if you don't have edit rigth and can't add a new field).
After calculating the lenght you could select or symbolise by attribute as usual
answered yesterday
J.RJ.R
3,546222
There are several way for that
If you just want to select line shorter than 500 you could use $length <500 (or $perimeter <500 if you're working with polygons) as an expression in the select by expression (the 500 is the length in the layer CRS unit, if you want 500m made sure to use a projected CRS whose unit is meters)
Alternatively you could calculate a length field in the attribute table using $length as expression (you could either create a new field (no auto-update if you edit the line but the value are added to your layer) or create a virtual field (auto-update on edit but the value only exist in this specific QGIS project, also usefull if you don't have edit rigth and can't add a new field).
After calculating the lenght you could select or symbolise by attribute as usual
answered yesterday
J.RJ.R
3,546222
answered yesterday
J.RJ.R
3,546222
answered yesterday
J.RJ.R
3,546222
answered yesterday
J.RJ.R
3,546222
3,546222
Fantastic! Using 'Processing Toolbox' > 'GQIS geoalgorithms' > 'Vector selection tools' > 'Select by expression' and putting in your suggested query I have got exactly what I wanted. Thank you
– John_Beatty
yesterday
Please accept the answer if he has solved your problem, so that other participants understand that a similar question can solve their problem.
– Cyril
yesterday
OK, done. I had to look up on Google to find out how to do this!
– John_Beatty
yesterday
add a comment |
Fantastic! Using 'Processing Toolbox' > 'GQIS geoalgorithms' > 'Vector selection tools' > 'Select by expression' and putting in your suggested query I have got exactly what I wanted. Thank you
– John_Beatty
yesterday
Please accept the answer if he has solved your problem, so that other participants understand that a similar question can solve their problem.
– Cyril
yesterday
OK, done. I had to look up on Google to find out how to do this!
– John_Beatty
yesterday
Fantastic! Using 'Processing Toolbox' > 'GQIS geoalgorithms' > 'Vector selection tools' > 'Select by expression' and putting in your suggested query I have got exactly what I wanted. Thank you
– John_Beatty
yesterday
Fantastic! Using 'Processing Toolbox' > 'GQIS geoalgorithms' > 'Vector selection tools' > 'Select by expression' and putting in your suggested query I have got exactly what I wanted. Thank you
– John_Beatty
yesterday
Please accept the answer if he has solved your problem, so that other participants understand that a similar question can solve their problem.
– Cyril
yesterday
Please accept the answer if he has solved your problem, so that other participants understand that a similar question can solve their problem.
– Cyril
yesterday
OK, done. I had to look up on Google to find out how to do this!
– John_Beatty
yesterday
OK, done. I had to look up on Google to find out how to do this!
– John_Beatty
yesterday
add a comment |
John_Beatty is a new contributor. Be nice, and check out our Code of Conduct.
John_Beatty is a new contributor. Be nice, and check out our Code of Conduct.
John_Beatty is a new contributor. Be nice, and check out our Code of Conduct.
John_Beatty is a new contributor. Be nice, and check out our Code of Conduct.
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Welcome to GSE ! Please try to add more context with the DEM source (if possible) and the tools used under QGIS. Have you a particular reason for begin with QGIS 2.8 ? If you want to learn using QGIS, I recommend you to start with the latest LTR 3.4 : qgis.org/en/site/forusers/download.html
– J. Monticolo
yesterday
Can you please explain what GSE stands for.I would start with 3.4 but am nervous of installing programs that haven't made it to my distributions repository
– John_Beatty
yesterday
GSE stands for Gis Stack Exchange, this site ! Since 2.8, QGIS have made great updates.
– J. Monticolo
yesterday
I bit the bullet, upgraded from Mint 18.2 to Mint 19.1 and now have QGIS 3.6 installed. Thank you for your suggestion.
– John_Beatty
2 hours ago