contributation.txt is empty

[caiya55]

hi, I am using the pov-ray software under the POV-Ray_3.7_for_RaySAR_compiled folder, I tried the Box.pov, it works well, and the Contributions.txt is generated. but when we change to my own .pov file and run it, the Contributions.txt is empty. I also change the pov file from C:\Users\zhang\Documents\POV-Ray\v3.7\scenes\advanced, I think this is the offical samples, but the contributions.txt is still empnty.

For each pov file, I added "global_settings {SAR_Output_Data 1 SAR_Intersection 0} "
thanks！

[StefanJAuer]

There are two possible reasons I can think of:

• the camera does not look at the object, i.e. the rays do not intersect with a surface. No contributions are detected. Please check the rendered optical image of the scene.
• the diffuse reflection coefficient is 0. No contributions are detected. I am not perfectly sure whether the file is empty then but this could be possible.

[yzhao93943]

I have the same problem and rendered (from the pov-ray) looks fine and why there are no contributions?

[skimtea]

@caiya55 Did you solve this problem？i got same trouble which i used my own .pov file and run it, the Contributions.txt is empty。。。。(你有解决这个问题吗？我也设置了"global_settings {SAR_Output_Data 1 SAR_Intersection 0} ")

[StefanJAuer]

There are two test models in the package (RaySAR_1.2/RaySAR_Test_Models) in combination with results that should be obtained when conducting the simulation. The POV-Ray file gives examples how the object definition is made (last text block), e.g.

object {step_model
translate <0,0,0> // adapt if necessary
rotate <0,0,0> // adapt second value for rotation (y -> height axis)
pigment {color White}
finish {reflection {0.5} ambient 0 diffuse 0.3 specular 0.7 roughness 0.005}
}

You may conduct the simulation for that model in order to test the functionality of RaySAR and check the structure of your POV-Ray file.

[skimtea]

@StefanJAuer Dr'Auer thanks ,i followed your suggestions to check my POV-Ray file which converted from a .3ds model file in PoseRay and i found a interesting phenomenon.
If I use the original Pov file, i will got a render image like that,but got empty Contribution.txt;

However when i change the camera projection type from pespective to orthographic, the Contribution.txt will contains the imaging parameters and the render image into an all-noise image

I have to admit I don't know much about ray tracing, so could you help me figure out this problem? Thank you very much!!

[StefanJAuer]

Okay, I understand. The writing process is coupled to the orthographic projection only (only this one resembles the nature of SAR imaging). Hence, using the perspective camera leads to an empty Contributions.txt.

Now, the image plane of the orthographic camera needs to be big enough to fully cover the object with its parallel rays. I'd assume that the current image plane is very small. Accordingly, you sample and see only a small piece of surface of the vehicle (likely at the turret).

Here's an example:

#declare Cam = camera {
orthographic
location <0,60,-60> // location of virtual SAR, far field -> orthographic projection
look_at <0,0,0>
right 100x // horizontal size of view
up 120y // vertical size of view
}

The values after "right" and "up" define the extent of the image plane. Adapt those to bring the vehicle completely on your image. Note that the number of rays in the image plane is defined in the resolution ini file.

[skimtea]

@StefanJAuer
Thanks Dr'Auer, i really appreciate your helps. With your advices i guess an underfitting image plane settings(include “right” and “up” define) resulted in empty Contribution.txt. So i changed some parameters in Camera settings (like "right" and "up") in a .pov file which have changed the camera type form perspective to orthographic .But i still got a strange image make me confused.The details of my experiment shown below.

The setting in perspective mode
#camera {
perspective
up <0,1,0>
right -x*image_width/image_height
location <-4.54747350886464E-13,1.13686837721616E-13,18162.552507674>
look_at <-4.54747350886464E-13,1.13686837721616E-13,18161.552507674>
angle 25.5987322094663 // horizontal FOV angle
rotate <0,0,0> //roll
rotate <-25,0,0> //pitch
rotate <0,45,0> //yaw
translate <-522.505493164063,827.611541748047,480.508056640625>
}

Geometric information about the target

The setting in orthographic mode
//CAMERA PoseRayCAMERA
#camera {
orthographic
up 4574y ##I resize the up&right based on the max coordinates
right 3268x
location <-4.54747350886464E-13,1.13686837721616E-13,18162.552507674>
look_at <-4.54747350886464E-13,1.13686837721616E-13,18161.552507674>
angle 25.5987322094663 // horizontal FOV angle
rotate <0,0,0> //roll
rotate <-25,0,0> //pitch
rotate <0,45,0> //yaw
translate <-522.505493164063,827.611541748047,480.508056640625>
}

The output strange image

i am urgent to solve this problem(maybe looks a little bit silly ), but i really hope you could help me.
i appreciate it very much!!