I’m new to PIX4D and need some help figuring out how to add GCP information using a total station points. I can start a project and all the photos look good . I know how to get to the GCP area, but when I add the xyz using total station points it throws the GCP point way across the country(blue x) from where my drone data shows my scene.
I’m sure I’m screwing up my output and GCP coordinate and output system , not sure if I should be in arbitrary?? and should I add where the total station was set up (0,0,0) for a GCP point ?? I tried sending support the info and they have me all turned around.
I’m sure this is simple task,but i cant find any step by step information for using total stations. I just need a step by step guidance if someone can please help me
I also believe that the coordinate systems of your project need some tuning. First, you need to make sure to know in which coordinate system (horizontal and vertical) your total station has made the measurements. This should be checked on your total station and is a prior knowledge required to correctly set the coordinate system in the software. This corresponds to the GCP coordinate system.
The geolocation of the images taken by your drone are also in a specific coordinate system. This is the image coordinate system and typically is WGS84.
Finally, you can select in which coordinate system you would like your results to be. This is the output coordinate system.
If there is one of those coordinate systems that is not correctly set, the coordinates you use as input will be used in a wrong coordinate system and the images or GCPs will end up at a wrong location.
The p4p is wgs84 when the photos are downloaded, but when I switch the output to feet it turns to nap1983arkansas(which is the correct area the area was mapped. I’ll check the total station for the coordinate system. I would assume that is where my problem lies, because when I add my first gcp ,the blue x ends up in Texas. Also as I mentioned earlier, do I add the stations position 0,0,0 as a ground control point wen I enter the other gcp information that we recorded?
Sorry to throw another question at you. we are trying to use pix4d to model crushed vehicles. We use the drone for the over head shots and a DJI OSMO and/or a Nikon digital camera for the ground level. When we process the pictures, the drone ones are fine but we get a lot of uncalibrated images from the ground cameras.
I have read up on the topic, but it seems we are still missing something. I know about the overlap and its better to have more than less. Obviously most times we are dealing with a shinier surface with paint and windows. just wonder if you have any recommendations to get better photos or something to help the photos process easier(was thinking adding some different ground targets around the vehicle so the photos would have something to match up)
Ill check the total station today and keep you updated, thanks again
My first thought on the oblique pictures is to fly the drone down near ground level or hold it in your hand without flying it so you get the same camera EXIF for all the pictures.
From the description, I assume that you used a total station and measured coordinates of GCPs in a local, arbitrary coordinate system and not in a known/state coordinate system.
If this is the case, you will need to set up the coordinate system of outputs and GCPs to Arbitrary.
Since the images are not directly linked to GCPs (different coordinate systems), the GCPs do not appear in the rayCloud and to mark them you need to use the Basic Editor. In the Basic Editor, you have to find each GCP in the image dataset.
For more information about how to use the basic Editor you can take a look here: https://support.pix4d.com/hc/en-us/articles/202557859
Or if marking the GCPs using the Basic Editor is very complicated you can use method B described in the following article: https://support.pix4d.com/hc/en-us/articles/202560239#label2.
As for the total station position (0,0,0), there is no need to define this position. What matters is that you precisely mark the GCPs in the project and perform the reoptimization afterward.
I hope the conversation is still active, as I understand that from the total station you only have to mark the gcp in the photos without fixing the origin 0,0,0.
I need to merge multiple subprojects, so how do I do it when I acquired every single facade?
I need to perform a local support with a polygonal and use the total station as the very complex geometry of the building does not allow you to beat all the points from a single point.
The mapping is of the facades overlooking a historic gallaria.
The topographical support must necessarily be done through a polygonal of several points via a total station as sub-centimeter precision is required. Moreover, the GNSS does not work on the facades.
So how do I assign an unique local reference system when I have several subprojects (nadir + facade 1 + facade 2, …) to be combined into a single final project?
I will merge every subproject through common MTPs, but the doubt remains on how the georeferencing of each single subproject can “flow” into the final local reference system of the model.
What is the coordinate system of the image geotags? Are you planning to georeference your project or to use an arbitrary coordinate system? It is recommended that all the subprojects have the same CS.
The coordinate system of images is WGS 84, but not always was recorded in every photos because of issues in reaching GPS signal during the flyght due to high density of buildings and structures all around.
I only have to georeference my project with high precision, so I set input image system as WGS 84 and arbitrary for the output in order to georeference with local system and GCPs acquired with total station and merge them with the same settings for every subproject and common MTPs.
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