[postgis-devel] [raster] Implementations of rotation and pixel size.

[Bborie Park]

Hey David,

Sigh.  Disregard my message about adding the hard limit of 90 degrees.
 I realized after I sent the prior email that one of my equations was
incorrect.

-bborie

On Fri, Sep 9, 2011 at 9:01 PM, Bborie Park <dustymugs at gmail.com> wrote:
> Hey David,
>
> I was wondering if you could add the hard limit of 90 degrees for
> RASTER_setRotation.  In writing what will become ST_Intersects(raster,
> raster), I was doing some testing on setting skew and what I realized
> is that as the numbers for skew (X and Y) get larger and larger, you
> get infinitely closer to plus/minus 90 degrees but will never there.
> As such, setting a limit saying that the rotation must be less than 90
> degrees sounds reasonable to me.
>
> -bborie
>
> On Thu, Aug 18, 2011 at 4:19 PM, dustymugs <dustymugs at gmail.com> wrote:
>> Hey David,
>>
>> I've looked at the patch attached to #482 and find no issues with it.
>> Everything (merging, compilation, regression testing and checking for memory
>> leaks) looks good.
>>
>> The only thing I changed with the patch remove the diff for GNUmakefile.in,
>> which is outside the raster directory.
>>
>> I have no recommendation to setting a hard limit of 90 degrees for
>> RASTER_setRotation.  It makes sense to me but I'd hope that Pierre chimes
>> in.
>>
>> -bborie
>>
>> On 08/18/2011 02:36 PM, David Zwarg wrote:
>>>
>>> Greetings raster devs,
>>>
>>> I took a day to implement the outstanding tickets that I had for some of
>>> the
>>> accessors related to rotated rasters:
>>>
>>>    - #928 - Implement ST_PixelWidth
>>>     <http://trac.osgeo.org/postgis/ticket/928>
>>>    - #929 - Implement ST_PixelHeight
>>>    <http://trac.osgeo.org/postgis/ticket/929>
>>>    - #936 - Implement ST_Rotation
>>>    <http://trac.osgeo.org/postgis/ticket/936>
>>>    - #482 - Implement
>>> ST_SetRotation<http://trac.osgeo.org/postgis/ticket/482>
>>>
>>> If someone could take a moment to review the patches attached to those
>>> tickets, that would be helpful. One of the things that I did not do was to
>>> limit the rotation amount in ST_SetRotation. I was reading more on the
>>> world
>>> file, and it sounds like a raster shouldn't be rotated more than 90
>>> degrees
>>> -- should that be a hard limit in ST_Rotation?  If the rotation exceeds 90
>>> degrees, does the affine transformation go haywire? In addition, the
>>> UpperLeft position should realistically be changed. Otherwise, you could
>>> technically define different rasters that cover the same area, but with
>>> different UpperLeft coordinates (imagine if the geotransform put the
>>> UpperLeft pixel at the lower right, and applied a 180 degree rotation).
>>>
>>> Thanks,
>>> David
>>>
>>>
>>>
>>>
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