[Qgis-user] Raster to Vector without losing the symbology
Nicolas Cadieux
njacadieux.gitlab at gmail.com
Mon Jul 19 15:19:03 PDT 2021
Hi,
I looked at your problem. Indeed, using the Group Stat plugin, you will
not be able to easily identify which polygon has the highest values.
You can export a csv with the cross tabulation results but there is
still no way to know which Polygon with the value A has highest value.
You can create a new field called "max" using the following expression.
maximum("Area",group_by:="Polygon")
That will giving you the highest value for each group. Then, you can
select polygon using the following expression
"Area" = "max"
Nicolas
On 2021-07-18 3:08 p.m., Nicolas Cadieux wrote:
> Use the extract value by location to get the values from the point
> back into the vector grid…
>
> Nicolas Cadieux
> https://gitlab.com/njacadieux <https://gitlab.com/njacadieux>
>
>> Le 18 juill. 2021 à 15:06, Nicolas Cadieux
>> <njacadieux.gitlab at gmail.com> a écrit :
>>
>>
>> Hi,
>>
>> Another way is to create a vector grid with the same size and pixel
>> posting as the original. Then, get the centroids and use the point
>> value tool to get the band values… This will give you a vector file
>> but the file will be heavy. You could merge the vector grids after to
>> merge values with similar values….
>>
>> Ask yourself if you really need a vector file first. This is not
>> always the best file format for you data.
>>
>> Nicolas Cadieux
>> https://gitlab.com/njacadieux <https://gitlab.com/njacadieux>
>>
>>> Le 18 juill. 2021 à 14:56, Nicolas Cadieux
>>> <njacadieux.gitlab at gmail.com> a écrit :
>>>
>>> Hi,
>>> You could create a style that could apply to both raster and vector
>>> layers but that would not help much here. The problem is that you
>>> need to create the vector based on one of the raster Bands and not
>>> all three. One way could be to combine all three fields into one.
>>> If your RGB is 155 025 255, make this a raster band with 155025255.
>>> Then, I guess you could use that 4th band to make the vector layer,
>>> then resplit the data into 3 fields and use that to create the
>>> colour profile.
>>>
>>> Nicolas Cadieux
>>> https://gitlab.com/njacadieux <https://gitlab.com/njacadieux>
>>>
>>>> Le 18 juill. 2021 à 12:51, krishna Ayyala <ayyalakrishna at gmail.com>
>>>> a écrit :
>>>>
>>>>
>>>> I have an image on my qgis map that has 3 bands. Band1 (red),
>>>> Band2(green) and Band3(blue). This image has different colors.Is it
>>>> possible to convert this image into a vector which should look
>>>> exactly like the image.
>>>>
>>>> That means; Is it possible to have the vector file that should have
>>>> the same colors as that of the image.
>>>>
>>>> Regards.
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--
Nicolas Cadieux
https://gitlab.com/njacadieux
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