José Luis García Pallero | 12 Dec 14:44 2009
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Verification of inverse step in projection

Hi,
I'm a new proj user and I have a doubt about the verification of
inverse step in projection. As the manual says (proj.4.3.pdf, page
41):

"Some projections do not have inverse capability; a state that can be
determined by proj->inv==0."

But when I try to test:

#include<proj_api.h>
......
projPJ pjStruct;
pjStruct = pj_init_plus("+proj=tcc +ellps=clrk66 +lon_0=90W");
if(!pjStruct)
    ....
if(pjStruct->inv==0)
    ....

At compilation time I obtain the error:

prueba.c: In function ‘main’:
prueba.c:22: warning: dereferencing ‘void *’ pointer
prueba.c:22: error: request for member ‘inv’ in something not a
structure or union

It says that inv is not a member of the projectios struct.
What is the correct way to check if a projection has inverse step?

Thanks
(Continue reading)

José Luis García Pallero | 12 Dec 18:10 2009
Picon

Verification of inverse step in projection

Hi,
I'm a new proj user and I have a doubt about the verification of
inverse step in projection. As the manual says (proj.4.3.pdf, page
41):

"Some projections do not have inverse capability; a state that can be
determined by proj->inv==0."

But when I try to test:

#include<proj_api.h>
......
projPJ pjStruct;
pjStruct = pj_init_plus("+proj=tcc +ellps=clrk66 +lon_0=90W");
if(!pjStruct)
   ....
if(pjStruct->inv==0)
   ....

At compilation time I obtain the error:

prueba.c: In function ‘main’:
prueba.c:22: warning: dereferencing ‘void *’ pointer
prueba.c:22: error: request for member ‘inv’ in something not a
structure or union

It says that inv is not a member of the projectios struct.
What is the correct way to check if a projection has inverse step?

Thanks
(Continue reading)

Joel_Cusick | 13 Dec 02:02 2009

Joel Cusick/AKSO/NPS is out of office


I will be out of the office starting  12/07/2009 and will not return until
12/14/2009.

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Roger Oberholtzer | 13 Dec 13:38 2009
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Re: Verification of inverse step in projection


On Dec 12, 2009, at 2:44 PM, José Luis García Pallero wrote:

> Hi,
> I'm a new proj user and I have a doubt about the verification of
> inverse step in projection. As the manual says (proj.4.3.pdf, page
> 41):
>
> "Some projections do not have inverse capability; a state that can be
> determined by proj->inv==0."
>
> But when I try to test:
>
> #include<proj_api.h>
> ......
> projPJ pjStruct;

Perhaps:

projPJ *pjStruct;

as pj_init_plus returns a pointer.

> pjStruct = pj_init_plus("+proj=tcc +ellps=clrk66 +lon_0=90W");
> if(!pjStruct)
>    ....
> if(pjStruct->inv==0)
>    ....
>
> At compilation time I obtain the error:
(Continue reading)

José Luis García Pallero | 13 Dec 15:25 2009
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Re: Verification of inverse step in projection

2009/12/13 Roger Oberholtzer <roger <at> opq.se>:
> Perhaps:
>
> projPJ *pjStruct;
>
> as pj_init_plus returns a pointer.
>
>
>> pjStruct = pj_init_plus("+proj=tcc +ellps=clrk66 +lon_0=90W");
>> if(!pjStruct)
>>    ....
>> if(pjStruct->inv==0)
>>    ....

But pj_init_plus() can't know if you will use the forward or the inverse step.

--

-- 
*****************************************
José Luis García Pallero
jgpallero <at> gmail.com
(o<
/ / \
V_/_
Use Debian GNU/Linux and enjoy!
*****************************************
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(Continue reading)

Roger Oberholtzer | 13 Dec 18:03 2009
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Re: Verification of inverse step in projection


On Dec 13, 2009, at 3:25 PM, José Luis García Pallero wrote:

> 2009/12/13 Roger Oberholtzer <roger <at> opq.se>:
>> Perhaps:
>>
>> projPJ *pjStruct;
>>
>> as pj_init_plus returns a pointer.
>>
>>
>>> pjStruct = pj_init_plus("+proj=tcc +ellps=clrk66 +lon_0=90W");
>>> if(!pjStruct)
>>>    ....
>>> if(pjStruct->inv==0)
>>>    ....
>
> But pj_init_plus() can't know if you will use the forward or the  
> inverse step.

These are two different issues:

1) You have a syntax error, which I tried to explain. That must be  
corrected no matter.

2) The function that does the actual transform is pj_transform. It  
takes to projPJ pointers. One describes the source data, and one  
describes the desired output. Swapping these two 'reverse' the  
transform.  Here is an example, with three functions. They are part of  
some larger system, but they should be clear enough to demonstrate the  
(Continue reading)

José Luis García Pallero | 13 Dec 19:13 2009
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Re: Verification of inverse step in projection

2009/12/13 Roger Oberholtzer <roger <at> opq.se>:
>
> On Dec 13, 2009, at 3:25 PM, José Luis García Pallero wrote:
>
>> 2009/12/13 Roger Oberholtzer <roger <at> opq.se>:
>>> Perhaps:
>>>
>>> projPJ *pjStruct;
>>>
>>> as pj_init_plus returns a pointer.
>>>
>>>
>>>> pjStruct = pj_init_plus("+proj=tcc +ellps=clrk66 +lon_0=90W");
>>>> if(!pjStruct)
>>>>    ....
>>>> if(pjStruct->inv==0)
>>>>    ....
>>
>> But pj_init_plus() can't know if you will use the forward or the
>> inverse step.
>
> These are two different issues:
>
> 1) You have a syntax error, which I tried to explain. That must be
> corrected no matter.

But the correct way of projPJ declaration is projPJ pjStruct because,
actually, projPJ is internally a pointer, as you can see in
http://trac.osgeo.org/proj/browser/trunk/proj/src/proj_api.h#L53
My problem is that I need to know if any projection has inverse step,
(Continue reading)

Roger Oberholtzer | 13 Dec 21:24 2009
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Re: Verification of inverse step in projection


On Dec 13, 2009, at 7:13 PM, José Luis García Pallero wrote:

> But the correct way of projPJ declaration is projPJ pjStruct because,
> actually, projPJ is internally a pointer, as you can see in

I was remembering incorrectly. projPJ is a typedef that is really  
either PJ *, or void *, depending on whether PROJECTS_H is defined.  
And this is defined if you include projects.h before the main proj  
include file. As I never access the inside of the struct, I do not  
include projects.h. But it seems to be needed if you want to access  
the inside of the struct.

Sorry for the confusion.

Roger Oberholtzer

OPQ Systems / Ramböll RST

Ramböll Sverige AB
Kapellgränd 7
P.O. Box 4205
SE-102 65 Stockholm, Sweden

Office: Int +46 8-615 60 20
Mobile: Int +46 70-815 1696

And remember:

It is RSofT and there is always something under construction.
(Continue reading)

José Luis García Pallero | 14 Dec 08:54 2009
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Re: Verification of inverse step in projection

2009/12/13 Roger Oberholtzer <roger <at> opq.se>:
>
> On Dec 13, 2009, at 7:13 PM, José Luis García Pallero wrote:
>
>> But the correct way of projPJ declaration is projPJ pjStruct because,
>> actually, projPJ is internally a pointer, as you can see in
>
> I was remembering incorrectly. projPJ is a typedef that is really
> either PJ *, or void *, depending on whether PROJECTS_H is defined.
> And this is defined if you include projects.h before the main proj
> include file. As I never access the inside of the struct, I do not
> include projects.h. But it seems to be needed if you want to access
> the inside of the struct.

Thanks, you are right. I can access now to the struct's members.
It's only need to include projects.h, that includes itself proj_api.h
(http://trac.osgeo.org/proj/browser/trunk/proj/src/projects.h#L243)

--

-- 
*****************************************
José Luis García Pallero
jgpallero <at> gmail.com
(o<
/ / \
V_/_
Use Debian GNU/Linux and enjoy!
*****************************************
_______________________________________________
Proj mailing list
Proj <at> lists.maptools.org
(Continue reading)

Michael P Finn | 15 Dec 22:06 2009
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CaGIS Scholarships


THE 2010 CARTOGRAPHY AND GEOGRAPHIC INFORMATION SOCIETY (CaGIS)
SCHOLARSHIPS

Each year, the Cartography and Geographic Information Society (CaGIS)
sponsors two scholarships to students whose research and accomplishments
support the mission of CaGIS. The scholarships recognize academic
achievement and encourage the continuing success of outstanding
cartography, geographic information systems (GIS), and geographic
information science (GIScience) students. The scholarships also recognize
achievement or potential for achievement in original research advancing the
specific disciplines of cartography or GIScience. Winners are selected
based on academic achievement, particularly in the calendar year prior to
the award. Applications are reviewed by the CaGIS Scholarship Committee,
and awards are announced in February or March. Information on other
CaGIS-sponsored awards is available at www.cartogis.org/awards.

Awards
CaGIS Masters Scholarship Award ($500): This award is to be granted to a
student enrolled in, or accepted into, a Masters’ degree program during
2009 or 2010. The winner will have demonstrated excellence in cartography
or GIScience coursework and the potential to contribute to cartography or
GIScience research. Outstanding undergraduates seeking to support
Masters’ level research in GIScience are also eligible to apply (see
below).

CaGIS Doctoral Scholarship Award ($1000): This award is to be granted to a
student enrolled in, or accepted into, a PhD degree program during 2009 or
2010. The winner will have demonstrated excellence in cartography or
GIScience coursework and the potential to contribute to cartography or
GIScience research.

Winners are invited to present their research at an upcoming
CaGIS-sponsored conference (such as AAG, GIScience, or AutoCarto) and may
be eligible for limited travel or registration support if they choose to
present.

Eligibility
Candidates must be enrolled full-time in a four-year undergraduate or
graduate degree program during 2009 or 2010, studying cartography,
geographic information science, or a closely related field. A letter of
recommendation from a faculty member attesting to these eligibility
requirements and to scholarly achievement and potential is required.
Membership in CaGIS is not required, though professional and service
activities such as participation in CaGIS is one of the selection criteria
(see below). Prior scholarship winners are eligible to apply in subsequent
years if all appropriate criteria are satisfied. Undergraduate applicants
who have not yet been accepted into graduate school should request that
their faculty advisor assess their potential for graduate study in their
reference letter.

Selection Criteria
Valid applications for CaGIS awards (see below for application procedures)
are reviewed by the CaGIS Scholarship Committee, which will use the
following criteria to judge applications:
•                 50% academic record;
•                 20% applicant’s statement;
•                 20% letter of recommendation;
• 10% professional activities (CaGIS membership, conference
participation, publications, community service, etc.).
Level of financial need will be considered, if necessary, to break ties,
after the primary criteria have been considered. The committee can choose
to award no scholarships.

Application Procedure
1.                 Go to http://www.cartogis.org/awards/ and complete the application form.
2.                 Compile the following:
•                 the completed application form
• a 400-word statement of educational objectives, future study or
research plans and professional activities, and relationship of activities
and/or research to mission of CaGIS
•                 a digital transcript showing records for 2009
• one letter of recommendation from a faculty member or supervisor
familiar with your work
3. E-mail these documents; see instructions on form. Applications must
arrive no later than 5:00pm CST on JANUARY 15, 2010.

Notification of Winners
The selected applicants for the scholarships will be notified on or near
February 15, 2010. The winners are encouraged to attend the awards ceremony
at the 2010 AAG conference or the 2010 AutoCarto conference (see
http://www.cartogis.org/eventspage/ for more information).

________________________________________
CaGIS Scholarship Committee:
Rob Edsall, Max Baber, and Michael Finn

Contact Information:
Rob Edsall, CaGIS Student Activities Coordinator
Department of Geography
414 Social Sciences Tower
University of Minnesota
267 19th Ave. S.
Minneapolis, MN 55455

phone: (612) 625-2562
e-mail: edsal001 <at> umn.edu






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