M4T RTK accurate or not ..

Dave Pitman · 2026-04-20T11:24:15-0400

DesmoMito said:
I’m struggling to understand the reason behind this difference.

If the focus of your survey is primarily the fidelity of the DSM (topography), then you want to use the nadir mission type.

If the the aesthetic of the 3D model is the primary goal, then the oblique mission is correct.

DesmoMito · 2026-04-20T11:54:21-0400

Thanks. In this case the focus of the survey was to test the accuracy of M4T with RTK (I've used Base+Rover approach - DJI RTK3 + M4T). Because I've seen here different results from what I've obtained I was wondering where I was wrong.

Dave Pitman · 2026-04-20T12:06:03-0400

At this point in the state of the processing technology, nadir image sets provide more accurate z values.

DesmoMito · 2026-04-20T12:39:16-0400

I think so but I don't understand why. And @jaja6009 has got different results. So I might have done something wrong.

Dave Pitman · 2026-04-20T13:09:12-0400

DesmoMito said:
I think so but I don't understand why. And @jaja6009 has got different results. So I might have done something wrong.

@jaja6009 error results for z on the M4T / Oblique without GCPs was over 1 foot. So worse than your 20cm. With GCPs, it dropped to .7 feet (21.34cm)

DesmoMito · 2026-04-20T14:45:12-0400

I refer to this test

Test 1 Nadir Images with Altitude Optimization, 5 Check Points, No GCPs.
X: 3.14 cm, Y: 1.95 cm, Z: 8.14 cm Total: 8.93 cm

Test 2 Smart Oblique, 5 Check Points, No GCPs and we have a winner!
X: 1.98 cm, Y: 1.98 cm Z: 3.26 cm Total: 4.29 cm

Dave Pitman · 2026-04-20T15:44:26-0400

I would consider that result, i.e that the smart oblique was better, as an anomaly comparing it to all of the other tests. Not the standard. Your own text confirmed that the nadir set produced better results. You need not take my word for it. Do a dozen more tests on your own and confirm it for yourself.

DesmoMito · 2026-04-20T16:57:42-0400

Dave Pitman said:
I would consider that result, i.e that the smart oblique was better, as an anomaly comparing it to all of the other tests. Not the standard. Your own text confirmed that the nadir set produced better results. You need not take my word for it. Do a dozen more tests on your own and confirm it for yourself.

Thank you. This is because oblique images (from Smart oblique) "confuse" more the photogrammetric process than just a few obliques in the "elevation optimizatione" mode ? Would it be better using the M4E ?