Ask about camera ssk parameter

[ThanhTrung128]

Hi author!
I have a question about camera ssk. Can you help me how to calculate some parameter of camera ssk?
Currently, I have some input as dom file (tiff), dsm file (tiff), point cloud (.ply) and image folder. I want to create Backward Projection ROI from point cloud file to original images. But I don't know how to create param folder as Lotus Pix4D dataset Because I don't have more knowledge about photo, or camera parameter. Can you help me?

[HowcanoeWang]

Hi,

The Lotus pix4d file structure may mislead you, I guess you are asking about the param_folder=lotus.pix4d.param right?

p4d = idp.Pix4D(project_path=lotus.pix4d.project,
                raw_img_folder=lotus.photo,
                param_folder=lotus.pix4d.param)

If you check lotus.pix4d.project, lotus_photo, lotus.pix4d.param using print() command, they are just path strings. And the param_folder is just optional, to tell the easyidp where is the pix4d project parameter folder

E.g.

/Users/..../xxxx.p4d  -> this is the pix4d project file
/Users/..../xxxx/     -> this is the pix4d parameter folder, by default no need to specify it

The Lotus Dataset gives that parameter because sometimes it needs to rearrange the folder structure for the data archive.

---

What you need to prepare later, is the *.shp file to represent the region that you want to convert. Since you already have the DOM and DSM file, it is recommended to use QGIS or ArcGIS to great that region, much easier than on pointcloud!

Please refer to this tutorial about how to make *.shp file:

https://easyidp.readthedocs.io/en/latest/backgrounds/roi_marking.html#marking-roi-on-gis-maps

[luongphambao]

Is it possible to use the backward projection (back2raw) method for custom dataset if I don't have access to the same parameters as those in 'lotus.pix4d.param'? Specifically, I have a shapefile, point cloud, DSM, and DTM that I would like to use.

[HowcanoeWang]

as mentioned above, what you need to do, should be:

p4d = idp.Pix4D(project_path=r"path/to/your/pix4d_project.p4d",
                raw_img_folder=r"path/to/your/uav_image_folder",
                param_folder=r"path/to/your/pix4d_project/")

[ThanhTrung128]

Can you share some knowledge how to create some parameter file in param folder?

[HowcanoeWang]

it is a folder created automatically by pix4d software when you save the project.

[HowcanoeWang]

To be more specific, it locates in pix4d_project/1_initial/params

Either

p4d = idp.Pix4D(project_path=r"path/to/your/pix4d_project.p4d",
                raw_img_folder=r"path/to/your/uav_image_folder")
# no need to handle that path by default

or

p4d = idp.Pix4D(project_path  =r"path/to/your/pix4d_project.p4d",
                raw_img_folder=r"path/to/your/uav_image_folder",
                param_folder  =r"path/to/your/pix4d_project/1_initial/params")

should work