[gdal-dev] gdaladdo without explicit factors specified

Jeff McKenna jmckenna at gatewaygeomatics.com
Wed Jun 28 05:38:06 PDT 2017

On 2017-06-28 9:10 AM, Even Rouault wrote:
> Hi,
> I'm pretty sure this must have annoyed a lot of people. When you run 
> gdaladdo, you need to specify the appropriate overview levels. Generally 
> you use power-of-two factors, but the question is then: what is the last 
> relevant factor given the dimension of my file size ?
> I've a ready to commit improvement where you can just do :
> gdaladdo [other options] my.tif
> and it will compute the appropriate power of two factors until the 
> smallest overview is smaller or equal to 256x256 (this threshould can be 
> adjusted with a new -minsize switch. Actually it should be named 
> -maxminsize, since this is the maximum size of the smallest overview, 
> but I guess -minsize will be clear enough)
> The effect of this patch is the same as specifying manually all the 
> overview factors implicitly computed. That means existing overview 
> levels will be recomputed if their factor match one of the implicitly 
> computed factors. Or they will be left unchanged if not matching one of 
> the implictly computed overview factors.
> Thoughts ?

I agree with Andrea.  I've been copy/pasting the command with the 
power-of-2 levels for almost 2 decades it seems ha, and I am sure 99% of 
the users do the same.  This is a great addition!


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