diff --git a/ohmg/extensions/iiif.py b/ohmg/extensions/iiif.py
index f1d0c492..6284a1e5 100644
--- a/ohmg/extensions/iiif.py
+++ b/ohmg/extensions/iiif.py
@@ -34,20 +34,23 @@ def get_target(self):
             wgs84.ImportFromEPSG(4326)
             mask_geojson = json.loads(self.layer.mask.geojson)
             coords = mask_geojson["coordinates"][0]
-            ct = CoordTransform(SpatialReference("WGS84"), SpatialReference("EPSG:3857"))
+
+            target_crs = f"EPSG:{self.region.gcpgroup.crs_epsg}"
+            ct = CoordTransform(SpatialReference("WGS84"), SpatialReference(target_crs))
             polygon = Polygon(coords)
             polygon.transform(ct)
 
-            g = Georeferencer(
-                crs=f"EPSG:{self.region.gcpgroup.crs_epsg}",
-                transformation=self.region.gcpgroup.transformation,
-                gcps_geojson=self.region.gcpgroup.as_geojson,
-            )
             in_path = (
                 self.region.file.url
                 if self.region.file.url.startswith("http")
                 else self.region.file.path
             )
+
+            g = Georeferencer(
+                crs=target_crs,
+                transformation=self.region.gcpgroup.transformation,
+                gcps_geojson=self.region.gcpgroup.as_geojson,
+            )
             g.make_gcps_vrt(in_path)
             ds = gdal.Open(g.gcps_vrt.get_vsi_url())
             transformer = gdal.Transformer(
@@ -57,10 +60,7 @@ def get_target(self):
                 ds,
                 # Transformer options that are ultimately passed to 'GDALCreateGenImgProjTransformer2()'
                 # https://gdal.org/api/gdal_alg.html#_CPPv432GDALCreateGenImgProjTransformer212GDALDatasetH12GDALDatasetHPPc
-                [
-                    ## need to update this, different number if thin plate spline
-                    "MAX_GCP_ORDER=1",
-                ],
+                g.make_transformer_options(),
             )
             transposed, status = transformer.TransformPoints(False, polygon.coords[0])
             coords_str = [f"{i[0]},{i[1]}" for i in transposed]
@@ -114,14 +114,15 @@ def get_gcps(self):
         return features
 
     def get_body(self):
-        if self.region.gcpgroup.transformation == "poly1":
-            transformation = {"type": "polynomial", "options": {"order": 1}}
-        elif self.region.gcpgroup.transformation == "tps":
-            transformation = {
-                "type": "thinPlateSpline",
-            }
-        else:
-            raise Exception("invalid transformation", self.region.gcpgroup.transformation)
+        match t := self.region.gcpgroup.transformation:
+            case "poly1":
+                transformation = {"type": "polynomial", "options": {"order": 1}}
+            case "tps":
+                transformation = {"type": "thinPlateSpline"}
+            case "helmert":
+                transformation = {"type": "helmert"}
+            case _:
+                raise Exception(f"invalid transformation: {t}")
 
         body = {
             "id": full_reverse("iiif_gcps_view", args=(self.layerid,)),
diff --git a/ohmg/extensions/urls.py b/ohmg/extensions/urls.py
index 65408ed4..e85ebc56 100644
--- a/ohmg/extensions/urls.py
+++ b/ohmg/extensions/urls.py
@@ -1,5 +1,6 @@
 from django.urls import path, register_converter
 
+from ohmg.extensions.feeds import PlaceFeed
 from ohmg.places.converters import PlaceConverter
 
 from .views import (
@@ -9,7 +10,6 @@
     IIIFResourceView,
     IIIFSelectorView,
 )
-from ohmg.extensions.feeds import PlaceFeed
 
 register_converter(PlaceConverter, "place-slug")
 
diff --git a/ohmg/frontend/svelte_components/src/components/interfaces/Georeferencer.svelte b/ohmg/frontend/svelte_components/src/components/interfaces/Georeferencer.svelte
index 73a53141..1785c5fe 100644
--- a/ohmg/frontend/svelte_components/src/components/interfaces/Georeferencer.svelte
+++ b/ohmg/frontend/svelte_components/src/components/interfaces/Georeferencer.svelte
@@ -173,21 +173,6 @@
       available: CONTEXT.user.perms.includes("core.use_helmert")
     },
   ];
-  $: {
-    if (gcpList.length == 3 && currentTransformation == "helmert") {
-      currentTransformation = "poly1"
-    }
-    if (currentTransformation == "helmert") {
-      minGCPs = 2;
-    } else {
-      minGCPs = 3;
-    }
-  }
-  $: {
-    if (gcpList.length <= 2 && currentTransformation != "helmert") {
-      previewMode = "n/a"
-    }
-  }
 
   let currentTargetProjection = 'EPSG:3857';
   const availableProjections = [
@@ -590,6 +575,19 @@
         note: props.note,
       });
     });
+
+    // special handling for helmert, do this before the preview is regenerated
+    if (gcpList.length == 3 && currentTransformation == "helmert") {
+      currentTransformation = "poly1";
+    }
+    if (currentTransformation == "helmert") {
+      minGCPs = 2;
+    } else {
+      minGCPs = 3;
+    }
+    if (gcpList.length <= 2 && currentTransformation != "helmert") {
+      previewMode = "n/a"
+    }
     getPreview();
   }
 
@@ -736,6 +734,16 @@
     return featureCollection;
   };
 
+  const preparePayload = function () {
+    return {
+      gcp_geojson: asGeoJSON(),
+      transformation: currentTransformation,
+      projection: currentTargetProjection,
+      sesh_id: sessionId,
+      last_preview_id: currentPreviewId,
+    }
+  }
+
   function getPreview() {
     if (currentTransformation == "helmert") {
       minGCPs = 2;
@@ -750,13 +758,7 @@
       `/georeference/${REGION.id}/`,
       CONTEXT.ohmg_post_headers,
       'preview',
-      {
-        gcp_geojson: asGeoJSON(),
-        transformation: currentTransformation,
-        projection: currentTargetProjection,
-        sesh_id: sessionId,
-        last_preview_id: currentPreviewId,
-      },
+      preparePayload(),
       (result) => {
         previewMode = previewMode == 'n/a' ? 'transparent' : previewMode;
         // updating this variable will trigger the preview layer to be
@@ -779,13 +781,7 @@
       `/georeference/${REGION.id}/`,
       CONTEXT.ohmg_post_headers,
       'submit',
-      {
-        gcp_geojson: asGeoJSON(),
-        transformation: currentTransformation,
-        projection: currentTargetProjection,
-        sesh_id: sessionId,
-        last_preview_id: currentPreviewId,
-      },
+      preparePayload(),
       () => {
         window.location.href = `/map/${REGION.map}`;
       },
@@ -901,17 +897,23 @@
   }}
   on:unload={cancelSession}
 />
-<div style="height:25px;">
-  Create 3 or more ground control points to georeference this document. <Link
+<div>
+  Create three or more ground control points to georeference this document. First, click on a recognizable spot
+  in the document on the left to begin the GCP. Then, click on that same location in the web map on the right
+  to complete it. Learn more about the process <Link
     href="https://docs.oldinsurancemaps.net/guides/georeferencing/"
-    external={true}>Learn more</Link
-  >
+    external={true}>in the docs</Link
+  >.
 </div>
 
-<ModalConfirm id="modal-submit-helmert" yesAction={submitSession}>
+<ModalConfirm id="modal-submit-helmert"
+  yesButtonText="Submit with two GCPs"
+  yesAction={submitSession}
+  noButtonText="Back to georeferencing"
+  >
   <p>
-    You have only two GCPs, but it is highly advisable to have three or more.
-    Please add more, unless you are unable to do so.
+    You have only created two GCPs, but we recommend having three or more.
+    If possible, please add more before submitting your work.
   </p>
 </ModalConfirm>
 <ModalConfirm id="modal-cancel"
diff --git a/ohmg/georeference/georeferencer.py b/ohmg/georeference/georeferencer.py
index d621bb98..36ac9f37 100644
--- a/ohmg/georeference/georeferencer.py
+++ b/ohmg/georeference/georeferencer.py
@@ -30,6 +30,7 @@ class HelmertParams:
     offset_x: float
     offset_y: float
 
+
 gdal.SetConfigOption("GDAL_NUM_THREADS", "ALL_CPUS")
 
 TRANSFORMATION_LOOKUP = {
@@ -300,6 +301,34 @@ def _get_helmert_params(self) -> HelmertParams:
             offset_y=offset_y,
         )
 
+    def _get_helmert_proj_pipeline(self) -> str:
+        ## fit the four-parameter Helmert model in one shot
+        params = self._get_helmert_params()
+
+        ## convert the rotation to arcseconds for the proj pipeline
+        arcseconds = (params.rotation + 90) * 3600
+
+        pipeline = (
+            "+proj=pipeline "
+            "+step +proj=axisswap +order=2,1 "
+            f"+step +proj=helmert +x={params.offset_x} +y={params.offset_y} "
+            f"+theta={arcseconds} +s={params.scale}"
+        )
+
+        return pipeline
+
+    def make_transformer_options(self) -> list[str]:
+        match self.transformation["id"]:
+            case "helmert":
+                pipeline = self._get_helmert_proj_pipeline()
+                logger.debug(f"applying: {pipeline}")
+                return ["SRC_METHOD=NO_GEOTRANSFORM", f"COORDINATE_OPERATION={pipeline}"]
+            case _:
+                return [
+                    f"DST_SRS={self.crs_wkt}",
+                    f"MAX_GCP_ORDER={self.transformation['gdal_code']}",
+                ]
+
     def cleanup_files(self):
         for vrt in [
             self.gcps_vrt,
@@ -355,61 +384,16 @@ def make_warped_vrt(
         self.make_gcps_vrt(src_path, out_name)
         self.warped_vrt = VRTHandler(out_name, as_variant="modified")
 
-        if self.transformation["id"] == "helmert":
-            ## fit the four-parameter Helmert model in one shot
-            params = self._get_helmert_params()
-
-            ## convert the rotation to arcseconds for the proj pipeline
-            arcseconds = (params.rotation + 90) * 3600
-
-            pipeline = (
-                "+proj=pipeline "
-                "+step +proj=axisswap +order=2,1 "
-                f"+step +proj=helmert +x={params.offset_x} +y={params.offset_y} "
-                f"+theta={arcseconds} +s={params.scale}"
-            )
-
-            logger.debug(f"applying: {pipeline}")
-
-            wo = gdal.WarpOptions(
-                creationOptions=[
-                    "BLOCKXSIZE=512",
-                    "BLOCKYSIZE=512",
-                ],
-                coordinateOperation=pipeline,
-                format="VRT",
-                dstSRS=f"{self.crs_code}",
-                transformerOptions=["SRC_METHOD=NO_GEOTRANSFORM"],
-                dstAlpha=True,
-                resampleAlg="nearest",
-            )
-        else:
-            wo = gdal.WarpOptions(
-                creationOptions=[
-                    #     "NUM_THREADS=ALL_CPUS",
-                    #     ## originally used this set of flags used
-                    #     # "COMPRESS=DEFLATE",
-                    #     ## should have been used PREDICTOR=2 with DEFLATE but didn't know about it
-                    #     # "PREDICTOR=2"
-                    #     ## useful in general but not needed when using COG driver
-                    "BLOCKXSIZE=512",
-                    "BLOCKYSIZE=512",
-                    #     ## advisable if using JPEG with GTiff, but not supported in COG
-                    #     # "JPEG_QUALITY=75",
-                    #     # "PHOTOMETRIC=YCBCR",
-                    #     ## Use JPEG, as recommended by Paul Ramsey article:
-                    #     ## https://blog.cleverelephant.ca/2015/02/geotiff-compression-for-dummies.html
-                    # "COMPRESS=JPEG",
-                ],
-                transformerOptions=[
-                    f"DST_SRS={self.crs_wkt}",
-                    f'MAX_GCP_ORDER={self.transformation["gdal_code"]}',
-                ],
-                format="VRT",
-                dstSRS=f"{self.crs_code}",
-                dstAlpha=True,
-                resampleAlg="nearest",
-            )
+        wo = gdal.WarpOptions(
+            creationOptions=[
+                "BLOCKXSIZE=512",
+                "BLOCKYSIZE=512",
+            ],
+            transformerOptions=self.make_transformer_options(),
+            format="VRT",
+            dstAlpha=True,
+            resampleAlg="nearest",
+        )
 
         try:
             gdal.Warp(str(self.warped_vrt.get_path()), self.gcps_vrt.get_vsi_url(), options=wo)
@@ -432,15 +416,6 @@ def make_trimmed_vrt(self, src_path, multimask_json_file: Path, layer_name: str)
             cutlineLayer=multimask_json_file.stem,
             cutlineWhere=f"layer='{layer_name}'",
             cropToCutline=True,
-            # srcAlpha = True,
-            # dstAlpha = True,
-            # creationOptions= [
-            #     'COMPRESS=JPEG',
-            # ]
-            # creationOptions= [
-            #     'COMPRESS=DEFLATE',
-            #     'PREDICTOR=2',
-            # ]
         )
         gdal.Warp(str(self.trimmed_vrt.get_path()), self.warped_vrt.get_vsi_url(), options=wo)
 
@@ -458,17 +433,9 @@ def make_cog(
         self.cog = Path(settings.TEMP_DIR, Path(src_path).stem + "-modified.tif")
 
         to = gdal.TranslateOptions(
-            # format="GTiff",
             format="COG",
-            # maskBand="mask",
             creationOptions=[
-                # 'COMPRESS=DEFLATE',
-                # 'PREDICTOR=2',
                 "COMPRESS=JPEG",
-                # 'TILED=YES',
-                # 'BLOCKXSIZE=512',
-                # 'BLOCKYSIZE=512',
-                # "PHOTOMETRIC=YCBCR",
                 "TILING_SCHEME=GoogleMapsCompatible",
             ],
             resampleAlg="nearest",