Surveying large area, 36 sq km, can I schedule with pix4d capture, GCP

Hi All,

-I have a Phantom 4 pro V2, and plan to survey a wide area: 5.75 km long and 7 km width in the bush, I have only 2 batteries, and 1 drone. can pix4D capture assist to cover this area, and see all block i am mapping? and how can I proceed. not sure to get internet access in that area, in an northern part of Cote d’Ivoire in a village.

-The second question can I know in advance how many image I will need to process and can PIX4D do that? the gaol of the study is to get a DTM and also an ortho photo,

  • How many GCPs can I set for this large scale project?


Hi Hamed,

Some clarifications, higher you fly, less images you will need to cover the whole area and lower will be your resolution (high GSD)
Therefore you flight plan (number of images) will depend on your needs (the desired resolution for your DSM and Ortho).

Internet connection is not required when using Pix4Dcapture. However do not forget that your drone cannot fly further than 2 km from the starting point otherwise the contact with the device will be lost.
Therefore you will need to set at least several missions to ensure that your drone stays in the connectivity zone.
I recommend you to plan several missions with significant overlap with 5 to 10 GCPs in each project (More GCPs do not contribute significantly to increase the accuracy) and then merge them into different projects.

More information:

Hope this will help.

Hi Marco,

thank you for the help; 

I though the Phatom 4 pro V2 can fly with connection to the controller up to 7km! how I just need to be in 2 km away from the drone?

I dont undertand? or it is based on pix4dcapture range?


Hi Hamed,

We have done some tests with our application.
If you use Pix4Dcapture and your furthest point is at 1000m, you will get a message saying " The drone might fly too far to ensure good connectivity during the mission". But it will not impede you from flying.
However if your furthest point is at 2000m, during the takeoff checklist you will get this message " Drone-Grid distance too large" which in this case will impede you from flying.
We recommend you rather to plan several flights with enough overlap and then merge your different projects.
You can still fly manually your drone at further distance and take image but beware with batteries.

Hope this will help.

Hi Marco,

thank you, I have devided my area in 1 sq km area, I get 56 area to cover with 56 flights. there is few hill on the area so it will help me adjust fly elevation.

I planned to set GCPs as tie points so that I can merge the projects easily later. Do I need also to set other GCPs inside  (5 or 10)  so that can be used later the the big merged project?

see google image. (red dot GCP tie point, green dot, GCPs for merged project).



Bonjour Hamed,

Usually it is recommended to have 5-10 GCPs per sub-projects. However it is possible to merge sub-projects that do not contain GCPs.
In the shared area it is good to have GCPs, but it will be more important to add MTPs (manual tie point) that are necessary for the merging.
I would like to mention that you are very optimistic with your project. Because having 56 flights with an average number of images about 500 images would result in a 28000 images projects which is really huge.
Largest Number of Images

If you do not have a very powerful computer, I doubt that you can really merge all your sub-projects together.
For such large project, it is recommended to work with large frame cameras.

Hope that you will make it with you project.


Bonjour Marco,

thank you for the advise, im around 560 image per block. and my laptop is prety good, a Alienware 15R2, 32 go ram, buying a ssd to process quikly; and my data are very well overlapped. 

I should be good.

Salut Hamed,

Bonne chance!

Bonjour Marc,

I get an error Warning w0009,

what is wrong with the data?


Bonjour Hamed,

This error could be due to many factors.

Could you provide a screenshot of the error message you get?


Hi Marco ,
I passed this step. 3 block has different projection.
Now merging , how long it can take to pass step 1?

Hi Hamed,

Could you clarify the issue your are facing?
You mean that you have three blocks in one of your projects? Or three of your projects have a different projection?

I cannot tell you it will take since it strongly depends on your hardware, the quality of your images, the number of images…

Feel free to upload your *.log file, *.p4d, quality report on this OneDrive so we can have a look.



Hi Marco,

have finally divided the project in 4 block each block containing 14 blocks,   dsm, Dtm and ortho photo created.

when done now I visualize the dtm in another software to see if they can stick together, few has different of 1 meter to 10 meters.

but the most strange is that one block have 50 to 20 m difference. I then remake the one I found odd because GCPS was at different altitude with DTM in some area in other area it was fine.

or do you think that I should use each subproject (subproject is made of 14 block of 560 image each) and merge again as a single project to get a single DTM with my laptop configuration.


Bonjour Hamed,

Could you share with us your quality reports?

But this height difference is weird. Are you marking and reoptimizing after inserting your GCPs?
Could you upload one of your project in the Cloud so I can have a look to your images?

Merging merged project should not be a problem if your computer is powerful enough.


Hi Marco,

finally I did an update and use the last version of pix4D, and the difference come to 1 to 10 m between each project.

all time I created the quality report it crashed.

just to recall, each project is made of 14 sub project. and I have 4 bloc like that. I ran all the step on thoses 4 projects.

Can I create a new merged project using the 4 big project as sub project?


Bonjour Hamed,

What do you mean by "The difference come to 1 to 10 between each project"?
Have you been able to complete the 3 steps for your subprojects? Only the first is needed if you want to merge your subprojects.

If you manage to pass the first step then you should be able to merge your projects if they contains MTPs with the same name.
I would like also to recall you that according to our system you are eligible for personal support.

Normally if your subprojects have been correctly processed there should not be any problem in merging.

Hope this will work!

Hi Marco,

the difference in elevation with the border of blocks created. 

we finaly merged all the project with a new workstation, and it works.

now only thing is few GCPS in the log report show 7 meter difference, and we can not genearte teh quality report it crash all the time.

just remind we have more than 33 000 images.