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Using Fisheye lens clipped onto mobile phone camera for terrestrial mapping

I am experimenting with using Pix4D for indoor mapping (capturing rooms) using a mobile phone camera and have had good results so far.

To capture a wider field of view I have bought a clip-on fish eye lens, which seems to capture reasonable quality images.  However, I do not seem to be able to get Pix4D to process them, and always get a camera calibration error.  I suspect I need to manually edit the camera model, but I do not know what settings to change.

I have created a new camera model type, changed the lens type to fisheye and set the Affine transformation C and F to the image width.

The images are currently rectangular from the phone, though the captured image is a circle: is this contributing to the problem?

Hi Bernard,

 

What do you mean by ¨The images are currently rectangular from the phone, though the captured image is a circle¨. Does this mean that your mobile phone automatically corrects the distortions of the images? This is something that you should avoid. You should import the distorted images into Pix4Dmapper.

 

To calibrate a fisheye camera:

 

  1. Open the Image Properties Editor and click Edit on the Select Camera Model tab. 
  2. Click Edit on the Camera Model tab. 
  3. Select Fish Eye Lens and input these values:
  • Sensor Width [mm]: The sensor width in millimeters.
  • Sensor Height [mm]: The sensor height in millimeters.
  • Polynomial coefficients: 0, 1, 0, 0, 0
  • Affine transformation C = image width in pixels
  • Affine transformation D = 0
  • Affine transformation E = 0
  • Affine transformation F = image width in pixel
  1. Run Step 1.
  2. Check the reconstruction of the model by assessing the Quality Report and by selecting automatic tie points around the model and checking the reprojection on the input images in the rayCloud.
  3. If the reconstruction is not good enough, then add Manual Tie Points in the areas that are not well reconstructed and Reoptimize: https://support.pix4d.com/hc/en-us/articles/202560349
  4. Regenerate the Quality Report and repeat Steps 5 and 6 until the reconstruction is satisfying.
  5. When the reconstruction is good:

    1. Open the Image Properties Editor and click Edit on the Select Camera Model tab. 
    2. Click Edit on the Camera Model tab. 
    3. Click Load Optimized Parameters, then OK and Yes. 
    4. Remove the Manual Tie Points.
    5. Re process Step 1.

The reconstruction should be good and the camera parameters can be used as initial values for other projects.
9. If the reconstruction is not good, then repeat steps 6-8.

 

Let us know if you need further help.

Best regards,

Hi Christina,

WIll these settings work if I am using a Nikon 10.5mm fisheye lens on a DSLR? We use this setup to create our stitched spherical images. I tried importing into Pix4D with less than successful results. Thank you for any guidance!

 

Tony G.

Hello Tony,

I do not understand exactly. Are you importing the Nikon images into Pix4D or the stitched images?

Would it be possible to get some images from your Nikkon camera?

Thank you very much.

Hey Daniel,

Thanks for getting back to me. I’m still researching and doing a little trial and error with the images. Once I started seeing how indoor mapping could possibly work for us, I wanted to check if our current equipment would be sufficient. 

We do a lot of interactive “virtual tour” type presentations using spherical images. Not sure if they will appear but I’ve attached two images. Our workflow involves taking several photos (like image1) then stitching them together to create a flattened image (image2).

The stitched photos are imported into another program with an embedded viewer that allows interactivity. We are using Nikon DSLRs with a 10.5mm fisheye lens. The DX crop is OFF which gives the circular appearance, otherwise the image would fill the frame.

So far in my reading, I see that the individual images can work if taken properly. Can stitched images work as well?

 

Hello again,

As you say, I do not think the stitched images will be accepted. I would use the original ones as fisheye. There is one Nikon fisheye camera in our database but I am not sure it is yours.

Regards.