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How to get values on a rastar layer to provide me with values

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1

So I have received data from an external source for my work they have provided me with NDUI (plant productivity) with black being a lower value and white a higher value, however I am unsure on how to get specific values for certain areas
Does anyone know how to get values up from this type of layer or do I need to ask the provider for additional information?

qgis

share|improve this question

edited 8 hours ago

Alison Jones

asked 8 hours ago

Alison JonesAlison Jones

33866 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  You got that the wrong way, white are high values, black are low values. Take a look at your layer window to the left. Also, what do you mean by "get values"? Manually write them down? Extract them? Use them for automatic processing?
  
  – Erik
  8 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  I would like to see the values for each area e.g. labelling so i can visually see them. Would that be possible?
  
  – Alison Jones
  8 hours ago
  

  
  
  
  

add a comment | 

1

So I have received data from an external source for my work they have provided me with NDUI (plant productivity) with black being a lower value and white a higher value, however I am unsure on how to get specific values for certain areas
Does anyone know how to get values up from this type of layer or do I need to ask the provider for additional information?

qgis

share|improve this question

edited 8 hours ago

Alison Jones

asked 8 hours ago

Alison JonesAlison Jones

33866 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  You got that the wrong way, white are high values, black are low values. Take a look at your layer window to the left. Also, what do you mean by "get values"? Manually write them down? Extract them? Use them for automatic processing?
  
  – Erik
  8 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  I would like to see the values for each area e.g. labelling so i can visually see them. Would that be possible?
  
  – Alison Jones
  8 hours ago
  

  
  
  
  

add a comment | 

So I have received data from an external source for my work they have provided me with NDUI (plant productivity) with black being a lower value and white a higher value, however I am unsure on how to get specific values for certain areas
Does anyone know how to get values up from this type of layer or do I need to ask the provider for additional information?

qgis

share|improve this question

edited 8 hours ago

Alison Jones

asked 8 hours ago

Alison JonesAlison Jones

33866 bronze badges

share|improve this question

edited 8 hours ago

Alison Jones

asked 8 hours ago

Alison JonesAlison Jones

33866 bronze badges

share|improve this question

edited 8 hours ago

Alison Jones

asked 8 hours ago

Alison JonesAlison Jones

33866 bronze badges

asked 8 hours ago

Alison JonesAlison Jones

33866 bronze badges

asked 8 hours ago

Alison JonesAlison Jones

33866 bronze badges

1 Answer
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3

There are a number of different ways to get values from a raster layer.

If you are interested in the value of a given pixel, you can use the Identify Features tool to query the raster and return the value of the selected pixel in each band of the image. Your data looks like a single-band Unsigned 8-bit image, so 0-255 would be what you should expect to see.

If you need to query numerous specific places, you can do a Sample Raster Values using an existing Point layer that has the specific locations you wish to sample against your raster. It will create a new output Point layer that will have the raster cell value assigned to each point. This would be most useful if you were looking to sample known tree crown locations and had them mapped already.

If you needed to sample a polygon, I would approach that by creating either Random or Regular points within a polygonal extent, and doing a Sample Raster Value against that extent. After that, you can do an Aggregate against those points to get summary statics for that extent (mean, median, mode, etc).

EDIT:

To label each specific pixel, you can run either Raster pixels to points or Raster pixels to polygons (I would personally choose points), set the Symbology to not draw any symbol, and set the Label to the VALUE field. This will put a centered label on each pixel representing the raster's value.

share|improve this answer

edited 5 hours ago

answered 8 hours ago

Saijin_NaibSaijin_Naib

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add a comment | 

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3

There are a number of different ways to get values from a raster layer.

If you are interested in the value of a given pixel, you can use the Identify Features tool to query the raster and return the value of the selected pixel in each band of the image. Your data looks like a single-band Unsigned 8-bit image, so 0-255 would be what you should expect to see.

If you need to query numerous specific places, you can do a Sample Raster Values using an existing Point layer that has the specific locations you wish to sample against your raster. It will create a new output Point layer that will have the raster cell value assigned to each point. This would be most useful if you were looking to sample known tree crown locations and had them mapped already.

If you needed to sample a polygon, I would approach that by creating either Random or Regular points within a polygonal extent, and doing a Sample Raster Value against that extent. After that, you can do an Aggregate against those points to get summary statics for that extent (mean, median, mode, etc).

EDIT:

To label each specific pixel, you can run either Raster pixels to points or Raster pixels to polygons (I would personally choose points), set the Symbology to not draw any symbol, and set the Label to the VALUE field. This will put a centered label on each pixel representing the raster's value.

share|improve this answer

edited 5 hours ago

answered 8 hours ago

Saijin_NaibSaijin_Naib

49111 silver badge66 bronze badges

add a comment | 

3

There are a number of different ways to get values from a raster layer.

If you are interested in the value of a given pixel, you can use the Identify Features tool to query the raster and return the value of the selected pixel in each band of the image. Your data looks like a single-band Unsigned 8-bit image, so 0-255 would be what you should expect to see.

If you need to query numerous specific places, you can do a Sample Raster Values using an existing Point layer that has the specific locations you wish to sample against your raster. It will create a new output Point layer that will have the raster cell value assigned to each point. This would be most useful if you were looking to sample known tree crown locations and had them mapped already.

If you needed to sample a polygon, I would approach that by creating either Random or Regular points within a polygonal extent, and doing a Sample Raster Value against that extent. After that, you can do an Aggregate against those points to get summary statics for that extent (mean, median, mode, etc).

EDIT:

To label each specific pixel, you can run either Raster pixels to points or Raster pixels to polygons (I would personally choose points), set the Symbology to not draw any symbol, and set the Label to the VALUE field. This will put a centered label on each pixel representing the raster's value.

share|improve this answer

edited 5 hours ago

answered 8 hours ago

Saijin_NaibSaijin_Naib

49111 silver badge66 bronze badges

add a comment | 

There are a number of different ways to get values from a raster layer.

If you are interested in the value of a given pixel, you can use the Identify Features tool to query the raster and return the value of the selected pixel in each band of the image. Your data looks like a single-band Unsigned 8-bit image, so 0-255 would be what you should expect to see.

If you need to query numerous specific places, you can do a Sample Raster Values using an existing Point layer that has the specific locations you wish to sample against your raster. It will create a new output Point layer that will have the raster cell value assigned to each point. This would be most useful if you were looking to sample known tree crown locations and had them mapped already.

If you needed to sample a polygon, I would approach that by creating either Random or Regular points within a polygonal extent, and doing a Sample Raster Value against that extent. After that, you can do an Aggregate against those points to get summary statics for that extent (mean, median, mode, etc).

EDIT:

To label each specific pixel, you can run either Raster pixels to points or Raster pixels to polygons (I would personally choose points), set the Symbology to not draw any symbol, and set the Label to the VALUE field. This will put a centered label on each pixel representing the raster's value.

share|improve this answer

edited 5 hours ago

answered 8 hours ago

Saijin_NaibSaijin_Naib

49111 silver badge66 bronze badges

share|improve this answer

edited 5 hours ago

answered 8 hours ago

Saijin_NaibSaijin_Naib

49111 silver badge66 bronze badges

answered 8 hours ago

Saijin_NaibSaijin_Naib

49111 silver badge66 bronze badges

answered 8 hours ago

Saijin_NaibSaijin_Naib

49111 silver badge66 bronze badges