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Telecom Manholes Processing and Acquisition TIps

I have been tasked to learn Pix4D and produce very clear zoom orthos of roadways with telecom manholes. Like some information regarding the best way to take the pictures of the manholes and then how to produce the zoom orthos?


In your case, a high-resolution orthomosaic with a fine Ground Sampling Distance is required. 
I would recommend using the Pix4Dcapture app, which enables users to perform automated missions over an area with a predetermined GSD that suits your needs. 

Afterwards, you can process the dataset in Pix4Dmapper using the DSM and Orthomosaic resolution 1 x GSD. The default 3Dmaps template will already give optimal results.

To get more information about the possibility to view the orthomosaic in third-party software I recommend checking:


Hi, thanks for the information. Since I will be photographing manholes that are on roadways, do you recommend in the PIX4Dcapture app I free fly or use one of the grid functions. 

Should I film with or without an ND filter?

What height is recommended?


Selecting a Grid mission in the Pix4Dcapture would be better as Free Flight type should only be used for a small project and experienced pilots. With the automated Grid mission, you also do not need to pay attention to the overlap as it is determined based on the settings in the app. On the other hand, some gaps might appear when flying manually.

You do not need to use an ND filter when the weather conditions are good. As the purpose of ND filter is to reduce the amount of light entering the camera through lenses you may find out that your images are underexposed when during image acquisition process was dark and cloudy. 

As a side note, adding any kind of filter on the lens can change the internal camera parameters (focal length, distortions etc.) and therefore we do not recommend using them for mapping.

The height of the mission depends on the required accuracy of the final results. If for example, you need to deliver an orthomosaic with 2 cm resolution, then I would suggest selecting a GSD less than 2 cm in the Pix4Dcapture. The Pix4Dcapture will then adjust your height parameter based on the GSD that you will choose. 


Hi, still have not been able to get a clear sharp picture of a manhole at 162 feet. I tried even using the DJI Go App and taking pictures at 162 feet above a manhole. Pictures still seem to be blurry. I am not using the automatic feature I am doing camera changes in manual mode.

ISO set to 100

Shutter Speed 800-1000

Aperture : adjust for picture quality

Any suggestions would be great.


In this case, the problem is not the processing options but the camera settings itself. If you wrongly set up the camera parameters, no matter which application you will use to capture the images, your results will be unsatisfied.

Please read carefully our article about configuring the camera before a flight here. The most important for you would be the Camera Settings paragraph. There you can find all the information and suggestions which you should follow during camera adjustment.

I am flying a DJI Phantom 4 Pro. I have the ISO 100, Aperture 28.8 and Shutter Speed at 1600 at 164 FT and flying at 16 mph. I tried to attach a picture but it was greater than 2MB. Any suggestions on how to get a clearer picture. Looks pretty good but the lettering is still a bit blurry.

The average GSD was 1.42 cm /0.56 in.

Please set the aperture to automatic and increase the shutter speed to 1/800 and check if it helps.

To share your data with us you can use a file sharing service: Google Drive, Dropbox, WeTransfer :)

Hi, I have attached a few pictures I took using the Pix4Dcapture.

Altitude 86ft

ISO 100 Fixed

Aperture automatic

Shutter Speed 1/800

Please look at the link of one of the photos that is not in focus. I appreciate any advice. I am flying a DJI Phantom 4 Pro and did not use any filter. 

Hi Steve,

I am not sure what you want to appreciate in the manholes but I think the images have enough quality.

I think you should maybe fly lower to get more resolution.