Hi Pix4D Support,
Does the Pix4Dcatch app benefit from the iPad Pro with Wi-Fi + Cellular model for remote outdoor captures as it has a built-in GPS/GNSS module?
iPad Pro (Gen 2) with LiDAR
- iPad Pro (Wi-Fi + Cellular) has built-in GPS/GNSS
- iPad Pro (Wi-Fi) has a digital compass (iBeacon microlocation). Therefore, it does NOT have GPS /GNSS module.
I understand that iBeacon microlocation positional accuracy is based on the number of available Wi-Fi routers it’s able to locate as a function of distance. This is a wonderful strategy for mapping indoor environments where Wi-Fi is available, but how does this strategy support outdoor remote data captures. On construction sites, Wi-Fi may not be available. Even if there is WiFi on a remote site, it would only serve as a single iBeacon. I would assume that a dual or tri-iBeacon would be a minimum requirement to provide reasonable positional accuracy.
I had tested the Pix4Dcatch app on an iPad Pro (Gen2) without cellular, on a couple remote job sites which consisted of 500-1000 images. None of these model stitch properly. Recently, I was re-evaluating the Pix4Dcatch app, when I turned-off Wi-Fi and a message in the app said “turn on Wi-Fi to improve location accuracy”. This is an important topic that Pix4D support should define in detail, as it pertains to the iPad Pro (Gen2) model (Wi-Fi vs. cellular) and it’s data positional accuracy in various environments.
Those of us on the UAV-side understand that GPS and image overlap are two very important functions in the image stitching algorithm. I believe it’s safe to assume that this also remains true for ground terrestrial data capture. Unless, the small/cheap cellular GPS/GNSS module is not accurate enough for ground capture. If so, I assume the app relies more heavily on LiDAR and IMU data for image stitching. Therefore, the stitching algorithms for the iPad Pro is different because the iPad data captures at a smaller-scale (ie. mm-cm range). In comparison to a drone that typically collects data over a greater distance (ie. meters), GPS data is a primary factor in the stitching algorithm.
I understand that Pix4D may not want to discourage iPad Pro (Wi-Fi) users against deploying/testing the new app, as Wi-Fi only iPad models makeup 90% of sales. However, for those of us who want to ensure a quality stitch, it’s best to understand the benefits of the cellular model now for early adoption. Users would be frustrated to learn that the iPad Pro (Wi-Fi only) device is presenting significant positional inaccuracy in outdoor environments, which could have otherwise been avoided at the Point-of-Purchase. We would like to be made aware if the cellular model iPad Pro is recommended now or even in the future (algorithm updates), for remote site captures where Wi-Fi is non-existent.
From a users perspective, learning that a 3D model did not stitch properly is not a gamble worth taking if we had initially bought the cellular iPad Pro model. It’s only $150 difference for an iPad Pro model with Wi-Fi + cellular. Knowing that the Pix4Dcatch app uses the cellular GPS/GNSS data is important to the users. We need to know what environment (indoor vs. outdoor) the iPad Pro model is more suitable when capturing data.
I understand people want to use the Pix4Dcatch app to merge aerial and terrestrial models (myself included), but are having a great level of difficulty doing so. I wonder if this is due to the lack of accuracy iBeacon microlocation data presents. Pix4D support, have you successfully merged the two models together (sample link)? Can this be compiled on the cloud or must the projects be merged on the desktop version of Pix4Dmapper?