Retiring BLAM and announcing fSpy - a stand alone camera matching app


(stuffmatic) #61

Can you give an example of a use case where it’s good to have the exact sensor dimensions in Blender? Or is it just about the satisfaction of knowing the values match :slight_smile: ?


(Steffen Dünner) #62

It’s for several reasons, only a small part of it is “satisfaction” :wink:
Mainly it’s to avoid confusion later in a project and to be able to directly compare focal lengths of shots without having to think around the corner every time because the sensor size could be whatever big.
And it’s for verification purposes as well. When the meta data (in a perfect world it’s intact and hasn’t been mangled by a post production) says 50mm lens and you do your camera reconstruction magic with fSpy and it says “49,97mm” you know you’re on the right track.
If weeks later the DOP comes to your studio and asks you “what lens are you using in this shot?” and you tell him “erm, a 10mm” but the shot doesn’t look like a wide angle shot because the sensor size was set to “iPhone 4s”, that’s bad.
And I also don’t want to switch between scenes, wondering why the look is so different although the lens is the same. Oh, someone fiddled with the sensor size, grrrr.
We like to work super clean and if we have to create new cameras in 3D we always use 35mm full frame, just to get “real-world” focal lengths. Sometimes I have a director sitting next to me telling me “yeah, and now give me a top shot, 18mm” and with the right sensor he gets the intended look instantly.
Don’t know it that’s enough of an explanation, but it would help me a lot to get the same sensor size in Blender and fSpy.


(kkar) #63

Hey it would be nice if the exporter script also sets paths for the reference image and sets it as cam back in Blender.

thanks


(stuffmatic) #65

The first beta version is available for download!

From now on, please use the importer add-on to get your camera parameters into Blender.


(kkar) #66

Did you just swear at me ? :slight_smile:


(Nanomanpro) #67

Unfortunately, small pictures still cause the “zoom out” effect:


(iarga) #69

Two suggestions:

  1. Sometimes the object I want to model, is rotated with respect to the lines (axis) I use for matching the perspective.
    Is it possible to make the 3D guides rotatable? So the 3D guide has a local orientation (axis) that can be used to aline the camera (to an already made object in blender)?

  2. (fSpy importer) Because I want to use multiple matched views for one object, is it also possible to possition the image in an image-empty before the camera (instead of a background image)?
    Now I do this time-consuming job manually.

I think that both suggestions are difficult (and takes hours, days…) to program, so I don’t expect you to implement this. I thank you again for your time and skill to make this nice software.


(iarga) #70

Great tip for aligning the pespective matched image/camera and “help-cube” (together) to an actual model:

@Okavango’s “NP Station” addon (point_align)


(RickyBlender) #71

@stuffmatic
is there a wiki page where we can find this new addon ?

also does this include an equivalent for the fspy ?

is fspy going to stay free or will become a paid soft ?

thanks
happy bl


(Bastian N) #72

Was anyone able to get this running in Blender? I downloaded the addon…it seems to install but Addon is not showing up. No Import options etc…


(stuffmatic) #73

Make sure you get download the latest version. There was an addon registration issue in a previous release. If it still doesn’t work, let me know.


(Bob Dowling) #74

This is just my ignorance, but I’m utterly unfamiliar with the “yarn” build system. (I’m an old school Makefile kind of guy.) What’s the relevant package to install to have the yarn build environment?

(Fedora 28 here.)


(Bastian N) #75

Now it works…! Thank you!


(3pointEdit) #76

I’ll certainly be sad that its not going to be built in to Blender now, as I loved using BLAM to support the motion tracker when it couldn’t grasp the sensor/lens dimensions. Is there a MAC version of the app? Instead of an importer is it possible to export a stripped down .blend file that consist of a dummy scene with the camera in it to append?


(stuffmatic) #77

fSpy is available for windows, linux and mac. For the mac version, look for fSpy-1.0.0.dmg in the downloads section

As for exporting .blend files, anything is possible :slight_smile: Haven’t looked into how feasible it is, but I agree it would be a nice feature.


(stuffmatic) #78

Maybe this will help? Feel free to create a github issue if you have further dev related questions.


(cekuhnen) #79

Pretty nice app - I have three question:

It seems you can move the position of the camera as you want vs BLAM


In the screenshot it states image/sensor proportion missmatch - what does this mean and how do I fix this?

it also seems that BLAM and fSpy get very different camera values.
In BLAM this was a 88.4 with fSpy this is a 73.7 field of view camera. how come?


(Okavango) #80

Seems like a great app. Unfortunately, i was unable to intstall from alpha 7 Appimage 64:

[4325:1115/211719.566895:FATAL:nss_util.cc(632)] NSS_VersionCheck(“3.26”) failed. NSS >= 3.26 is required. Please upgrade to the latest NSS, and if you still get this error, contact your distribution maintainer.


(stuffmatic) #82

It seems you can move the position of the camera as you want vs BLAM

If you perform calibration using BLAM and move the camera around without rotating it, you’ll notice that the perspective still matches regardless of the position of the camera. fSpy removes this degree of freedom by allowing the user to specify exactly where in the image the 3D origin should be. BLAM just placed the camera in an arbitrary position and left it up to the user to move it after calibration had been performed.

In the screenshot it states image/sensor proportion missmatch - what does this mean and how do I fix this?

This means that the aspect ratio of the sensor (1.5) is not the same as the aspect ratio of the image (about 1.3 in your example). This could indicate that either the wrong sensor size has been entered or that the image has been cropped in a way that changed its aspect ratio. Note that this is just a warning. If the fSpy preview looks reasonable, you should get the exact same result when importing to Blender.

it also seems that BLAM and fSpy get very different camera values.
In BLAM this was a 88.4 with fSpy this is a 73.7 field of view camera. how come?

Hard to say without knowing your exact Blender camera settings for the BLAM calibration. You will definitely notice if the field of view value is off by more than 10 degrees. Does your result look reasonable?


(stuffmatic) #83

Perhaps you’re having the issue discussed in this thread?