I'm doing Simulation of Synthetic Aperture Radar( SAR )Mode/(Microwave Imaging).

I came to through POV in one of the IEEE research paper and I thought it would
be useful for me. There is one segment in my project is scene object
reflectivity pattern calculation say the object can be building or car or tree
etc...

How to calculate the reflectivity pattern using any of the Electromagnetic
Imaging Algorithm like Ray Tracing Method / Physical Optics(PO) Method. I
suppose that POV can help me on that. It would be very helpful, if i get any
sort of suggestion from this group. At least let me know if my understanding is
correct or not ?

Thanks

Post a reply to this message

You probably need to specify in more detail what you mean by
reflectivity pattern.

Also, you should be aware that povray can only give you estimates
on the intensity of reflected light based on simple geometric models,
in particular not taking into account effects like interference. This
may limit the usefulness for simulating longer wavelengths.

Post a reply to this message

> I'm doing Simulation of Synthetic Aperture Radar( SAR )Mode/(Microwave Imaging).
>
> I came to through POV in one of the IEEE research paper and I thought it would
> be useful for me. There is one segment in my project is scene object
> reflectivity pattern calculation say the object can be building or car or tree
> etc...
>
> How to calculate the reflectivity pattern using any of the Electromagnetic
> Imaging Algorithm like Ray Tracing Method / Physical Optics(PO) Method. I
> suppose that POV can help me on that. It would be very helpful, if i get any
> sort of suggestion from this group. At least let me know if my understanding is
> correct or not ?
>
> Thanks
>
>

You can not simulate any interference pattern from several sources or 
reflective objects. The best you can get is thin film irisation. A very 
narow slit can't show anything but a sharp pattern. Those are crutial 
for any SAR.

For the visible spectrum, you can add some reflection in the finish of 
your objects. Metals have prety uniform reflectivity, but other 
materials normaly have variable reflection.

Post a reply to this message

Christian Froeschlin <chr### [at] chrfrde> wrote:
> You probably need to specify in more detail what you mean by
> reflectivity pattern.
>
> Also, you should be aware that povray can only give you estimates
> on the intensity of reflected light based on simple geometric models,
> in particular not taking into account effects like interference. This
> may limit the usefulness for simulating longer wavelengths.

Thanks for replying...

I mean reflectivity pattern here as BACK SCATTERING effect of the objects in the
scene. Like calculation of single, double and triple bounce effect from the
ray.. When all these effects are summed together we get, back scattering effect
of the object.I need reflectivity map of any 3D modeled object. I may not
require to consider the effects of interference. Just a simple creation of
reflectivity map of any object/ scene. Thank you.

Post a reply to this message

Alain <kua### [at] videotronca> wrote:

> > I'm doing Simulation of Synthetic Aperture Radar( SAR )Mode/(Microwave Imaging).
> >
> > I came to through POV in one of the IEEE research paper and I thought it would
> > be useful for me. There is one segment in my project is scene object
> > reflectivity pattern calculation say the object can be building or car or tree
> > etc...
> >
> > How to calculate the reflectivity pattern using any of the Electromagnetic
> > Imaging Algorithm like Ray Tracing Method / Physical Optics(PO) Method. I
> > suppose that POV can help me on that. It would be very helpful, if i get any
> > sort of suggestion from this group. At least let me know if my understanding is
> > correct or not ?
> >
> > Thanks
> >
> >
>
> You can not simulate any interference pattern from several sources or
> reflective objects. The best you can get is thin film irisation. A very
> narow slit can't show anything but a sharp pattern. Those are crutial
> for any SAR.
>
> For the visible spectrum, you can add some reflection in the finish of
> your objects. Metals have prety uniform reflectivity, but other
> materials normaly have variable reflection.

Thanks a lot for replying to my query...

Just simple level reflectivity map calculation of the object is only im looking
for.. Manually creating a program for Electromagnetic imaging like say Ray
tracing Algorithm , Physical optics method etc is very tedious task...

Thats why I'm planning to use POV ray for reflectivity map calculation of the
scene or object. From that generated reflectivity map, I was hoping to use it
for SAR raw echo simulation....

Is my approach feasible one ? Thank you.

Post a reply to this message

Mahadeesh wrote:

> I mean reflectivity pattern here as BACK SCATTERING effect of the objects in the
> scene. Like calculation of single, double and triple bounce effect from the
> ray.. When all these effects are summed together we get, back scattering effect
> of the object.I need reflectivity map of any 3D modeled object. I may not
> require to consider the effects of interference. Just a simple creation of
> reflectivity map of any object/ scene. Thank you.

It sounds like what you want to achieve could be approximated by
a light source (possibly a spot light if you have a confined beam),
diffuse textures for the back scattering, and radiosity for the
bounces. With the caveat that the light model for diffuse reflection
probably does not accurately reflect microwave backscattering.

I'm still not quite sure what the end result should be. A normal
render (camera image) would give you an image of the scene indicating
how much light is reflected into the direction of the camera for each
point of the object. If the camera and the light source are in the
same location that is probably an approximation of an "echo".

If you are more interested in the effect of the  object on the
surrounding you can put a sphere around the object and see how this is
illuminated through radiosity. If you want some total measure of light
scattered from each position of the object regardless of direction,
things are likely to get tricky although the mesh camera might help.

Post a reply to this message

Am 25.03.2013 06:38, schrieb Mahadeesh:

> Just simple level reflectivity map calculation of the object is only im looking
> for.. Manually creating a program for Electromagnetic imaging like say Ray
> tracing Algorithm , Physical optics method etc is very tedious task...
>
> Thats why I'm planning to use POV ray for reflectivity map calculation of the
> scene or object. From that generated reflectivity map, I was hoping to use it
> for SAR raw echo simulation....
>
> Is my approach feasible one ? Thank you.

I must confess that what you're saying is mostly dutch to me, and I'm 
probably not the only one here; you may need to think of us as stupid 
laymen when it comes to radar science, who need each and every technical 
term explained.

What, to begin with, is a "reflectivity map" as you understand it?

Post a reply to this message

clipka <ano### [at] anonymousorg> wrote:
> Am 25.03.2013 06:38, schrieb Mahadeesh:
>
> > Just simple level reflectivity map calculation of the object is only im looking
> > for.. Manually creating a program for Electromagnetic imaging like say Ray
> > tracing Algorithm , Physical optics method etc is very tedious task...
> >
> > Thats why I'm planning to use POV ray for reflectivity map calculation of the
> > scene or object. From that generated reflectivity map, I was hoping to use it
> > for SAR raw echo simulation....
> >
> > Is my approach feasible one ? Thank you.
>
> I must confess that what you're saying is mostly dutch to me, and I'm
> probably not the only one here; you may need to think of us as stupid
> laymen when it comes to radar science, who need each and every technical
> term explained.
>
> What, to begin with, is a "reflectivity map" as you understand it?

Hi,

Sorry for the inconvenience caused... I will definitely post the complete
details soon..
Thanks a lot.

Regards,
M

Post a reply to this message

Christian Froeschlin <chr### [at] chrfrde> wrote:
> You probably need to specify in more detail what you mean by
> reflectivity pattern.
>
> Also, you should be aware that povray can only give you estimates
> on the intensity of reflected light based on simple geometric models,
> in particular not taking into account effects like interference. This
> may limit the usefulness for simulating longer wavelengths.


Hello,

I mean here by reflectivity map is that the target scattering ability i.e.
Electromagnetic scattering of the object. Photographic images that contain only

both the amplitude and the phase information of the scattered EM field from the
scene. But it is very adruous to exactly  simulate scattering of EM field for
each object in the scene.

Hence Im thinking of using POV for giving the values of reflected light
intensity of any scene which is equivalent to reflectivity property of each
object of the scene( may be an approximation I can say).  Presently,Im not
interested in interference effects which will potentially complicate the problem
of SAR image formation.

This an sample SAR image :
https://www.google.co.in/search?q=SAR+image&hl=en&client=ubuntu&hs=bEM&channel=fs&tbm=isch&tbo=u&source=univ&sa=X&ei=Us
xaUZHQMcSIrQebm4GgDA&ved=0CDAQsAQ&biw=1067&bih=713#hl=en&client=ubuntu&hs=cZ1&channel=fs&tbm=isch&sa=1&q=synethetic+ape
rture+radar+image+&oq=synethetic+aperture+radar+image+&gs_l=img.3...14733.26980.4.27340.34.31.3.0.0.0.154.2713.29j2.31.
0...0.0...1c.1.8.img.j2PiLVDb-G4&bav=on.2,or.r_qf.&bvm=bv.44697112,d.bmk&fp=9cd1c99b78ac4f1a&biw=1067&bih=713&imgrc=kuh
ug3D1KiKnvM%3A%3BhL2JrnPfbrQReM%3Bhttp%253A%252F%252Fwww.sandia.gov%252FRADAR%252Fimages%252Fcapitol.jpg%3Bhttp%253A%25
2F%252Fwww.sandia.gov%252FRADAR%252Fimageryku.html%3B1200%3B800

You can note in the image that there are bright spots which is outcome of the
material property and surface. For example, the metal objects will reflect more
when compared with others. Similarily any sharp edges in the building will
produce more bounce effect which makes the spot brighter.

Also note the showdows in the SAR image. These are very much useful in many
remote sensing applications.Finally my intention is to form an SAR image as
shown in the example. Hence complete image generation depends on the
Reflectivity property of the objects in the scene.

Please revert back to me for any sort of question regarding the work.

Regards,
M

Post a reply to this message

Alain <kua### [at] videotronca> wrote:

> > I'm doing Simulation of Synthetic Aperture Radar( SAR )Mode/(Microwave Imaging).
> >
> > I came to through POV in one of the IEEE research paper and I thought it would
> > be useful for me. There is one segment in my project is scene object
> > reflectivity pattern calculation say the object can be building or car or tree
> > etc...
> >
> > How to calculate the reflectivity pattern using any of the Electromagnetic
> > Imaging Algorithm like Ray Tracing Method / Physical Optics(PO) Method. I
> > suppose that POV can help me on that. It would be very helpful, if i get any
> > sort of suggestion from this group. At least let me know if my understanding is
> > correct or not ?
> >
> > Thanks
> >
> >
>
> You can not simulate any interference pattern from several sources or
> reflective objects. The best you can get is thin film irisation. A very
> narow slit can't show anything but a sharp pattern. Those are crutial
> for any SAR.
>
> For the visible spectrum, you can add some reflection in the finish of
> your objects. Metals have prety uniform reflectivity, but other
> materials normaly have variable reflection.


Hello,

Thanks for replying to my mail. I would like to tell you that, presently im not
looking at interference pattern.

Im planning to generate reflectivity map of any object in the scene. As you
said, it depends on the material property. So we cant simulate each and every
object on the scene to get exact reflectivity property. Hence we have to come to
an approximate method for reflectivity pattern of the Object. Can POV help me on
that ?

Can you please tell me how to add the reflectivity property of the object at its
finish as you mentioned earlier in the scene ? Because adding these values can
improve the final SAR image generation.Also is it possible extract those
reflectivity values from any RGB image ?

I have given sample SAR image for you reference.

https://www.google.co.in/search?q=SAR+image&hl=en&client=ubuntu&hs=bEM&channel=fs&tbm=isch&tbo=u&source=univ&sa=X&ei=Us
xaUZHQMcSIrQebm4GgDA&ved=0CDAQsAQ&biw=1067&bih=713#hl=en&client=ubuntu&hs=cZ1&channel=fs&tbm=isch&sa=1&q=synethetic+ape
rture+radar+image+&oq=synethetic+aperture+radar+image+&gs_l=img.3...14733.26980.4.27340.34.31.3.0.0.0.154.2713.29j2.31.
0...0.0...1c.1.8.img.j2PiLVDb-G4&bav=on.2,or.r_qf.&bvm=bv.44697112,d.bmk&fp=9cd1c99b78ac4f1a&biw=1067&bih=713&imgrc=kuh
ug3D1KiKnvM%3A%3BhL2JrnPfbrQReM%3Bhttp%253A%252F%252Fwww.sandia.gov%252FRADAR%252Fimages%252Fcapitol.jpg%3Bhttp%253A%25
2F%252Fwww.sandia.gov%252FRADAR%252Fimageryku.html%3B1200%3B800

Please let me know if you need more details for my side. Thanks once again.

Regards,
M

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