Fix #3355 (#3381)

* fix nonzero colmap K4

nerfstudio/data/dataparsers/colmap_dataparser.py

@@ -276,6 +276,12 @@ class ColmapDataParser(DataParser):
             cy.append(float(frame["cy"]))
             height.append(int(frame["h"]))
             width.append(int(frame["w"]))
+            if any([k in frame and float(frame[k]) != 0.0 for k in ["k4", "k5", "k6"]]):
+                raise ValueError(
+                    "K4/K5/K6 is non-zero! Note that Nerfstudio camera model's K4 has different meaning than colmap "
+                    "OPENCV camera model K4. Nerfstudio's K4 is the 4-th order of radial distortion coefficient, while "
+                    "colmap/OPENCV's K4 is 4-th coefficient in fractional radial distortion model."
+                )
             distort.append(
                 camera_utils.get_distortion_params(
                     k1=float(frame["k1"]) if "k1" in frame else 0.0,