[yt-users] a question on camera with volume rendering

[Sam Skillman]

Hi Renyue,

If you can describe the galaxy using a data object (sphere, disk, etc), you
could then do something like galaxy_object.quantities['BulkVelocity']() to
get the motion of just that piece of the data.  I'm not sure if that is
helpful for you or not.

I would say that it would be best to get on a more recent version of yt,
where you will be able to use the tranpose, and the north vector will make
more sense with option 1 or 3.

Sam


On Mon, Jan 14, 2013 at 7:25 AM, Renyue Cen <cen at astro.princeton.edu> wrote:

> Hi Sam,
>
> I am using option (2) below without transpose (per your suggestion to fix
> the symmetric image problem)
> and it does seem to point to the right (I have a bit trouble to decide
> exactly at which direction the galaxy
> is traveling even though I have its peculiar velocity, because I do not
> have information about
> the velocity of the volume it is in).
>
> Thanks,
> Renyue
>
>
>
> On Jan 14, 2013, at 10:17 AM, Sam Skillman wrote:
>
> Hi Renyue,
>
> It depends a bit on how you are saving the image, unfortunately.  If you
> are using a recent changeset of yt (after 2.4 where the transpose causes
> symmetric images on some compilers/machines), and you save with:
>
> cam.snapshot('image1.png')
> Then image1.png will have north pointing up.
>
> If you did:
> im = cam.snapshot()
> write_bitmap(im, 'image2.png', tranpose=False)
> Then image2.png will have north pointing right.
>
> If you did
> im = cam.snapshot()
> write_bitmap(im, 'image3.png', transpose=True)
> Then image3.png will have north pointing up.
>
> I am working on ways to make sure that it always points up by using the
> new ImageArray class, but have not come up with the full solution yet.  I
> hope that description helps.
>
> Sam
>
>
>
> On Sat, Jan 12, 2013 at 8:12 PM, Renyue Cen <cen at astro.princeton.edu>wrote:
>
>> Hi,
>>
>> I think I am unclear about the orientation in pf.h.camera(c,W,L, ...,
>> north=vec, ...).
>> I  got some nice looking pictures but don't know what north means in this
>> case,
>> because when I switch north=vec to north=reverse of vec, the image
>> rotates along the vertical direction,
>> so it seems like north is pointing to either left or right.  It is very
>> desirable for me to be able
>> to make sure which direction vec points to (vec is the vec in north=vec)
>> in the final rendered plot.
>>
>>
>> Thanks in advance for help,
>> Renyue
>
>
>
>
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